5*6+4x=46
解30+4x=46
4x=16
x=4
8x-18+4=8
解8x=22
x=2.75
6x+5*7=77
解6x+35=77
x=7
1.2x+0.16/0.2=3.2
1.2x+0.8=3.2
x=2