数学问题：将一个正方形纸片剪去一个宽4cm的长条后，再从长方形纸片上剪下一个宽5cm的长条，剪下的两个长条面积相等，长条的面积是多少?

数学题解答：先画图，和图形有关的题目，如果能够先画出图形，则对于理解题意和解答题目都很有帮助。

设正方形的边长为x厘米。

则有：4x=5(x-4)

解这个方程，得x＝20，即正方形边长为20厘米。

据此算出长条面积为：20×4＝80（平方厘米）或（20-4）×5＝80（厘米），问题得到解决。

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