Find the values that make this a parallelogram?

The parallelogram is a square ans the values are:

on the outside of it is 17 y and 8y on the top and on the bottom it is 10 and 8x

On the inside of the square it is (3y-20) on the left hand corner and on the right hand it is (4y+4)
on the left hand bottom 4x+6 and right hand bottom (2x+6)