Since it's a rectangle, the sides across from eachother are equal.
5x = 3x + 18 and 3y – 7 = 2y + 4
With that information you can solve for x and y. Let's start with x.
5x = 3x + 18
5x – 3x = 3x – 3x + 18
2x/2 = 18/2
x = 9
3y – 7 = 2y + 4
3y – 2y – 7 = 2y – 2y + 4
y – 7 + 7 = 4 + 7
y = 11
x = 9; y = 11