Question

(6y^2-7y-3)-(2y^2-9y-7) simplify

Answer 1

6y^2-7y-3-2y^2+9y+7 (pretend that you're multiplying -1 to 2y^2-9y-7 which is why 9y and 7 are positive now).
Now you're able to simplify your problem, so...

6y^2-2y^2= 4y^2
-7y+9y= 2y
-3+7=4

4y^2+2y+4

Might want to check my math but that's how you do it.