5x-3.7=8.5
5x=8.5+3.7
5x=12.2
x=12.2/5
x=2.44
x-13=104
x=104+13
x=117
3x-x=41.6
2x=41.6
x=41.6/2
x=20.8
4x/1/2==0.8
4x=0.8*2
4x=1.6
x=1.6/4
x=0.4