题目内容：

分式3x\(x-4y)与(x+y)\(4y-x)的和减去7y\(x-4y)所得的差为?

优质解答

3x/(x-4y)+(x+y)/(4y-x)-7y/(x-4y)
=3x/(x-4y)-(x+y)/(x-4y)-7y/(x-4y)
=(3x-x-y-7y)/(x-4y)
=(2x-8y)/(x-4y)
=2