Through the process of substitution and re-arranging, you will be able to figure out the value of y.
First, plug in your x-value to start.
Now you just have to re-arrange the formula to isolate y by itself. So if you have another number there, then just move that to the other side. Whatever you do on one side, do for the other side.
All you need to do is to isolate/separate y by itself. The number/coefficient before a variable is usually what you need to divide because it's being multiplied by the y-value. Remember the balance rule for both sides.
From there, you will be given your y-value.
However, there's a trick. When a negative divides a negative, it always results in a positive.