17+2x=29
2x=29-17
2x=12
x=6
13×7+4x=127
91+4x=127
4x=127-91
4x=36
x=9
9x-2=2.5
9x=2.5+2
9x=4.5
x=4.5/9
x=0.4
3x-0.9=0.6×4
3x=2.4+0.9
3x=3.3
x=1.1