Serious Need help with some Math

Two variables require two equations to solve them. There is only one given. Perhaps you need to put random values of x and then find the values of y. E.g, put 1,2,3,4,5 in place of x and then find the value of y for each of them.

Example:

9x - 18y = 36
Let x = 2
9*2 - 18y = 36
-18y = 36 - 18
-18y = 18
-y = 1
y = -1