2(x+y)-3(x-2y)
问题描述：
2(x+y)-3(x-2y)
3b-2c-（-4a+3（c+3b））+3c-4a
答
2(x+y)-3(x-2y)
=2x+2y-3x+6y
=8y-x
3b-2c-（-4a+3（c+3b））+3c-4a
=3b-2c+4a-3c-9b+3c-4a
= -6b-2c