Is there not infinite solutions for r?
I think you are missing some restrictions.
Use similar triangles
3/5 = (x+3)/20
Solve for x
4/5 = (y+4)/20
Solve for y
Do these 2 on your own ;)
3/5 = (x+u+3)/60 plug in x to get u
4/5 = (v+y+4)/60 plug in y to get v