(3)0.5x-0.3=0.2x+1.2(4)3x-5+2x=4x-3(5)9.1+x-0.1+x=8.6乘3(6)1.12x+(x-3)+x=153(7)4x-(300-3x)=40乘3

(3)0.5x-0.3=0.2x+1.20.3x=1.5x=5(4)3x-5+2x=4x-33x+2x-4x=5-3x=2(5)9.1+x-0.1+x=8.6*32x=25.8-9.1+0.12x=16.8x=8.4(6)1.12x+(x-3)+x=1531.12x+x+x=153+33.12x=156x=50(7)4x-(300-3x)=40*34x+3x=120+3007x=420x=60