Question 55508
2r^2+3r-20s^2 from 4r^2-25s^2 
4r^2-25s^2 - (2r^2+3r-20s^2) 
4r^2-25s^2 - 2r^2-3r+20s^2
4r^2-2r^2 -25s^2+20s^2-3r [Combine like-terms]
2r^2 -5s^2-3r