(4x-2)*30%+2=(7x+8 )*20%
(4x-2)*0.3+2=(7x+8 )*0.2
1.2X-0.6+2=1.4X+1.6
1.2X-1.4X=1.6+0.6-2
-0.2X=0.2
X=-1
够详细了吧!