已知x-y=3则5(x-y)-3x+3y-2=

问题描述:

已知x-y=3则5(x-y)-3x+3y-2=

5(x-y)-3x+3y-2=
=5(x-y)-3(x-y)-2
=2(x-y)-2
=2×3-2
=4