3.6+x=5.4
x=5.4-3.6
x=1.8
1.8x减11.2=6.5
1.8x=6.5+11.2
x=17.7/1.8
x=9又5/6
3×0.4+4x=2.5,
4x=2.5-1.2
x=1.3/4
x=0.325
12x减6x=7.8
6x=7.8
x=7.8/6
x=1.3