8+z=17
z=9
_________________________
x-31=12
x=43
___________________
t - 7 = 16
t=23
___________________
15y=90
y= 90 : 15
y=6
_____________
6y = - 18
y= - 3
______________
12t=0
t=0
______________
3x=1,2
x=1,2:3
x=0,4
_________________
6z= - 5,4
z= - 0,9
____________________
1,2y=1,2
y=1
_______________________