请教一道模考题

margland

A tailor trims 4feet from opposite edges of a square piece of cloth and 5 feet from the other two edges. If 120 square feet of cloth remain , what was the length of a side of the original piece of cloth?
a 12 b 20 c 24 d 26 e40
答案是b20 我不太理解这个是怎么割的,这块布,看了答案还说不懂

tongxun

（x-4）（x-5）=120
x^2 -9x +20=120
x^2 -9x +140=0
我所能理解的就是这样了，但割不出20来（可能我想错了）
我的理解：
长缩短了4F，宽缩短了5F，则剩下的东西就从一个正方形变成一个长方形。

真的不好意思，没真正解答出来。

margland

it seems that (x-8) (x-10)=120  than the answer is 20

northying

为什么减8？
布的方形布的对边－4F，另2个对边－5F。或许是长方形裁成正方形。
这是我猜的，解释的英文是什么？

tongxun

I do not agree with you margland，because there is no such word as respectively in the question to illustrate cutting 5 feet in two sides。Would you mind copying the answer here， giving us an opportunity to discuss this question and thus figure it out？

northying

还是正方形裁成长方形。。。

我也希望看原版英文的解释。

fengqiwu

from opposite edge(s) 和 from the other two edge(s)应该是指四个边吧,如果这样,则应为(x-8) (x-10)=120 ,正方型裁成长方形

northying

clever

Thanks