[Q. ] 請問OG計量203題
A store currently charges the same price for each towel that it sells. If the
current price of each towel were to be increased by $1, 10 fewer of the
towels could be bought for $120, excluding sales tax. What is the current
price of each towel?
Ans. $3
我從網路上找的解答:
current price-x
current quantity-y
x*y=120
current price increased by 1 =(x+1)
current quantity decreased by 10=(y-10)
(x+1)*(y-10)=120
solving two equations
x^2+x-12=0
x=3
GRE版有人討論這題
也沒有下文
想請問高手這題
xy=120及(x+1)*(y-10)=120 如何從題目中看出
謝謝
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