For this equation the easiest thing to start with ratios:
16:4 (scale of 4 due to 4 x 4 being = to 16)
For the y-2 to find y you first will put 8/4 (your scaling back), so 2 so 4-2 would be 2 which makes that equal to y.
Knowing that 8 is the size on the one side these are equal on the top so x-3 had to equal 8, so 11-3=8 so...
x=11
y=2