13-2x=4
-2x=4-13
-2x=-9
x=4.5
3x+4*0.5=9.8
3x=9.8-2
3x=7.8
x=2.6
5(x+4)=55
x+4=11
x=11-4
x=7
9/(1.5x)=8
9=8*1.5x
12x=9
x=0.75
1.3x+x=13.8
2.3x=13.8
x=6
x-0.7x=6.9
0.3x=6.9
x=23
2x-8=1.4
2x=1.4+8
2x=9.4
x=4.7
1.8x=4
x=4/1.8
x=9分之20