1
4x+3=390:29
4x+3=13 13/29
4x=13 13/29-3
4x=10 13/29
x=10 13/29:4=303/(29*4)=303/116=2 71/116
2
5x-7=528:16
5x-7=33
5x=33+7
5x=40
x=40:5
x=8
3
8x-55=594:18
8x-55=33
8x=55+33
8x=88
x=88:8
x=11
4
6x+17=725:21
6x+17=34 11/21
6x=34 11/21-17
6x=17 11/21
x=17 11/21:6=368/(21*6)=368/126
x=2 116/126=2 58/63