1.4x-1.6*5=1.8 1.4x-8=1.8 1.4x=9.8 x=7 3(x+2)=4(x+1) 3x+6=4x+4 3x-4x=4-6 -1x=-2 x=2 12x+1.5=5.1 12x=5.1-1.5 12x=3.6 x=3 2.5x-0.9=8 2.5x=8+0.9 2.5x=8.9 x=3.56 够详细吧!
