航空百大

標題:

MATHS QUESTION

• 中文小組討論(好既40分)
• Ex13A 8, 10, 28, 30
• Valentine's Day

• 中文小組討論(好既40分)
• Ex13A 8, 10, 28, 30
• Valentine's Day

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發問:

HELP ME YO SOLVE THIS MATHS QUSTION : 30 x ( 1 - r% ) = 20 x ( 1 + r% )

最佳解答:

證明: 30*(1-r%)=20*(1+r%) 30-30r%=20+20 r% 30-20=20r%+30r% 10=50r% 1/5=r% 1/5=1/100r r=20 驗證(左邊):30*(1-20%) =30*80% =30*0.8 =24 (右邊):20*(1+20%) =20*120% =20*1.2 =24

其他解答:

30x(1-r/100)=20x(1+r/100) 30-30r/100=20+20r/100 30-0.3r=20+0.2r 0.5r=10 r=20|||||30 -30r =20 +20r 10=50r r=10/50 r=0.2 %|||||30 x (1-r%) = 20 x (1+r%) 30-30r% = 20+20r% 30-20=30r%+20r% 50r%=10 r%=0.2 r=20|||||30 x ( 1 - r% ) = 20 x ( 1 + r% ) 30 - 30r% = 20 + 20r% 20r% + 30r% = 30 - 20 50r% = 10 50r / 100 = 10 50r = 1000 r = 20|||||30 - 0.3r = 20 + 0.2r 10 = 0.5 r r = 20