Let sth be x
5x+10=8
5x=-2
x=-2/5
x=-0.4
Step-by-step explanation:

Answer:
x = s, y = t, z = 8 -s -t
Step-by-step explanation:
It can work reasonably well to let s and t represent any of a pair of the variables. In the answer above, we have used x=s, y=t.
You could get more elaborate if you want:
x = 4-s, y = 4-t, z = s+t
You would use order or operations to solve this problem
4 to the second power is 16 -------> 12+16= 28
Your answer would be 28