2.5x-1.8+0.5x=0.6 15.6-2(x-7.4)=12.4 0.86*2-7.1x=0.3 35-x=4(

2.5x-1.8+0.5x=0.6
3x=0.6+1.8
x=0.8
15.6-2(x-7.4)=12.4
15.6-2x+2*7.4=12.4
-2x=12.4-15.6-2*7.4
-2x=-18
x=9
0.86*2-7.1x=0.3
-7.1x=0.3-1.72(0.86*2的积)
-7.1x=-1.42
x=0.2
35-x=4(x+5)
35-x=4x+4*5
35-20=4x+x
5x=15
x=3