1.31-2z=15
-2z=15-31
-2z=-16
z=-16/2
z=8
2.7-y=15
-y=15-7
-y=8
y=8
3.3+0.1x=14
0.1x=14-3
0.1x=11
x=11/0.1
x=11*10
x=110
4.1.2t+0.4=1
1.2t=1-0.4
1.2t=0.6
t=0.6/1.2
t=6/12
t=0.5
1.31-2z=15
-2z=15-31
-2z=-16
z=-16/2
z=8
2.7-y=15
-y=15-7
-y=8
y=8
3.3+0.1x=14
0.1x=14-3
0.1x=11
x=11/0.1
x=11*10
x=110
4.1.2t+0.4=1
1.2t=1-0.4
1.2t=0.6
t=0.6/1.2
t=6/12
t=0.5