(6f^2 - 9f + 10) - ( -2f^2 - f + 3)
So first, you have to distribute the minus in the middle. You ALWAYS have to. So when you do that, the minus changes to a plus, and everything on the right side of it changes from positive to negative or negative to positive. So it would turn into this -
(6f^2 - 9f + 10) + (2f^2 + f - 3)
Now, you can combine like terms. Add each one that matches. (Add the ones that have 1 f, or f^2)
Answer:
8f^2 - 8f + 7