標題:
幫忙一算英文數學題...10分(方程式)
發問:
1.Donna buys some $2 stamp and some $5 stamp. If she spends $54 altobether and gets 15 stamp , how many $2 stamp does she buy ?????2.A sum of $120 is divided between two sister . The elder sister spends 1/5 of the amount received white the younger sister spends 1/6 of the amount received . If the elder sister... 顯示更多 1.Donna buys some $2 stamp and some $5 stamp. If she spends $54 altobether and gets 15 stamp , how many $2 stamp does she buy ????? 2.A sum of $120 is divided between two sister . The elder sister spends 1/5 of the amount received white the younger sister spends 1/6 of the amount received . If the elder sister spends $13 more than the younger sister , how much does each of them receive?????? 求快點.... 已經知答案.... 1.7 2.elder sister :$90 ,younger : $30 求算式!!!thx
(1) Let the number of $2 stamps he buy be y, then the number of $5 stamps he buys is (15-y) 2y+5(15-y)=54 2y+75-5y=54 3y=21 y=7 Therefore he buys 7 $2 stamps. (2) Let the elder sister receive $y, then the youger sister receives $(120-y) y/5-(120-y)/6=13 6y-5(120-y)=390 6y-600+5y=390 11y=990 y=90 Therefore the elder sister receives $90, then the youger sister receives $(120-90)=$30.
其他解答:
1. Let x be the number of $2 stamp that Donna buys Let y be the number of $5 stamp that Donna buys x + y =15 ............................1 2x+5y=54 .............................2 1x2 = 2x+2y=30.................3 2-3= 3y=24 y=8 because x+y=15 so x+8=15 x=7 so she buy 7 $2 stamp 2. Let x be the elder sister received Let y be the younger sister received x + y=120 x=120-y........................1 x/5-y/6=13 x-5y/6=65 6x-5y=390.......................2 6(120-y)-5y=390 720-6y-5y=390 330=11y y=30 because x+y=120 x+30=120 x=90 so the elder sister received $90 the younger sister received $30|||||1. Let x be the number of $ 2 stamp and the number of $5 stamp 15 -x . 2 x + 5 ( 1 5 - x ) = 5 4 2 x + 7 5 - 5 x = 5 4 - 3 x = - 2 1 x = 7 She buy 7 $ 2 stamp. 2 Let x be the money elder sister has. and younger sister has 120 -x . 1 / 5 x - 1 / 6 ( 120 -x ) = 1 3 1 / 5 x - 2 0 + 1 / 6 x = 1 3 1 1 / 3 0 x = 3 3 x = 9 0 Elder sister has $90 and younger sister has $30|||||1. let there are x $2 stamp so no. of $5 stamp = 15-x 2x + 5(15-x) = 54 2x + 75 -5x = 54 3x = 21 x = 7 so she buy 7 $2 stamp 2. let elder sister receive $x, so younger sister = $(120-x) (1/5)x - (1/6)(120-x) = 13 6x - (600-5x) = 390 11x = 990 x = 90 so elder sister receive $90 younger sister = $(120-90) = $30|||||1.let x be the $2 stamps she has y be the $5 stamps she has x+y=15 --------- 1 2x+5y=54 ----------2 Form 1, x=15-y ------- 3 Sub 3 into 2, 2x+5y=54 2(15-y)+5y=54 30-2y+5y=54 3y=24 y=8 so, she buy 8 $2 stamps 2. let x be the money the elder sister received y be the money the younger sister received x+y=120 ------- 1 (1/5)x-(1/6)y=13 --------- 2 Form 1, x=120-y ------- 3 Sub 3 into 2, (1/5)x-(1/6)y=13 (1/5)(120-y)-(1/6)y=13 (120-y)/5-y/6=13 720-6y-5y=390 -11y=-330 y=30 So, the elder sister received $120-30=$90 the younger sister received $30 2006-10-31 19:13:43 補充： [修正] so, she buy (15-8)=7 $2 stamps
幫忙一算英文數學題...10分(方程式)
發問:
1.Donna buys some $2 stamp and some $5 stamp. If she spends $54 altobether and gets 15 stamp , how many $2 stamp does she buy ?????2.A sum of $120 is divided between two sister . The elder sister spends 1/5 of the amount received white the younger sister spends 1/6 of the amount received . If the elder sister... 顯示更多 1.Donna buys some $2 stamp and some $5 stamp. If she spends $54 altobether and gets 15 stamp , how many $2 stamp does she buy ????? 2.A sum of $120 is divided between two sister . The elder sister spends 1/5 of the amount received white the younger sister spends 1/6 of the amount received . If the elder sister spends $13 more than the younger sister , how much does each of them receive?????? 求快點.... 已經知答案.... 1.7 2.elder sister :$90 ,younger : $30 求算式!!!thx
此文章來自奇摩知識+如有不便請留言告知
最佳解答:(1) Let the number of $2 stamps he buy be y, then the number of $5 stamps he buys is (15-y) 2y+5(15-y)=54 2y+75-5y=54 3y=21 y=7 Therefore he buys 7 $2 stamps. (2) Let the elder sister receive $y, then the youger sister receives $(120-y) y/5-(120-y)/6=13 6y-5(120-y)=390 6y-600+5y=390 11y=990 y=90 Therefore the elder sister receives $90, then the youger sister receives $(120-90)=$30.
其他解答:
1. Let x be the number of $2 stamp that Donna buys Let y be the number of $5 stamp that Donna buys x + y =15 ............................1 2x+5y=54 .............................2 1x2 = 2x+2y=30.................3 2-3= 3y=24 y=8 because x+y=15 so x+8=15 x=7 so she buy 7 $2 stamp 2. Let x be the elder sister received Let y be the younger sister received x + y=120 x=120-y........................1 x/5-y/6=13 x-5y/6=65 6x-5y=390.......................2 6(120-y)-5y=390 720-6y-5y=390 330=11y y=30 because x+y=120 x+30=120 x=90 so the elder sister received $90 the younger sister received $30|||||1. Let x be the number of $ 2 stamp and the number of $5 stamp 15 -x . 2 x + 5 ( 1 5 - x ) = 5 4 2 x + 7 5 - 5 x = 5 4 - 3 x = - 2 1 x = 7 She buy 7 $ 2 stamp. 2 Let x be the money elder sister has. and younger sister has 120 -x . 1 / 5 x - 1 / 6 ( 120 -x ) = 1 3 1 / 5 x - 2 0 + 1 / 6 x = 1 3 1 1 / 3 0 x = 3 3 x = 9 0 Elder sister has $90 and younger sister has $30|||||1. let there are x $2 stamp so no. of $5 stamp = 15-x 2x + 5(15-x) = 54 2x + 75 -5x = 54 3x = 21 x = 7 so she buy 7 $2 stamp 2. let elder sister receive $x, so younger sister = $(120-x) (1/5)x - (1/6)(120-x) = 13 6x - (600-5x) = 390 11x = 990 x = 90 so elder sister receive $90 younger sister = $(120-90) = $30|||||1.let x be the $2 stamps she has y be the $5 stamps she has x+y=15 --------- 1 2x+5y=54 ----------2 Form 1, x=15-y ------- 3 Sub 3 into 2, 2x+5y=54 2(15-y)+5y=54 30-2y+5y=54 3y=24 y=8 so, she buy 8 $2 stamps 2. let x be the money the elder sister received y be the money the younger sister received x+y=120 ------- 1 (1/5)x-(1/6)y=13 --------- 2 Form 1, x=120-y ------- 3 Sub 3 into 2, (1/5)x-(1/6)y=13 (1/5)(120-y)-(1/6)y=13 (120-y)/5-y/6=13 720-6y-5y=390 -11y=-330 y=30 So, the elder sister received $120-30=$90 the younger sister received $30 2006-10-31 19:13:43 補充： [修正] so, she buy (15-8)=7 $2 stamps
文章標籤
全站熱搜
留言列表
