book Maths Puzzle Numerical Ability

No matter how I try, I am not understanding this type of problem....
3x -2y + 5z
____________
2y -3x -5z

This is how I try....
3x (3x-2y + 5z) -(2y + 5z)
_________

Read Solution (Total 0)

book Other Question

explain how to work this problem
2x 4y- 3(7x -2y)
determine the constant term in the expansion of (x + 2)^9