2x-17=97
2x=97+17
2x=114
x=57
7x-4.8=0.8
7x=0.8+4.8
7x=5.6
x=0.8
x除2.5＝80
(x/2.5)*2.5=80*2.5
x=200
1.6+3.2x=7.68
3.2x=7.68-1.6
3.2x=6.08
x=1.9