Determine X and Y

Answer 1

36x - 3y = 3
reduce to

12x - y = 3
or
y = 12x -3

There are an infinite number of solutions
pick any x you feel like, then evaluate the corresponding y
e.g.
x = 1
y = 12(1)-3 = 12-3 = 9

x = -3.56
y = 12(-3.56) -3 = -45.72

etc.

To have the instruction:
"Determine X and Y" is simply much too vague.