Question

5x-2y=30 when x=8 what's y?

Answer 1

5(8)-2y=30
40-2y=30
2y=10
y=5

Answer 2

5x-2y=30 when x=8

First: Plug in your y
It should look like: 5(8)-2y=30
Next: You will simplify 
It should look like: 40-2y=30
Then: You would subtract 40 on each side
It should look like: 2y=-10
Last: You will divide each side by -2
You should get: y=5 as your answer

HOPE THIS HELPS! ^_^