Hi there!
To subtract this, we can only subtract like terms. That means we only subtract 7x^2 and 5x^2, 4x and 10x, and -9 and -5. It might make more sense after the work below:
7x^2 - 5x^2 = 2x^2
4x - 10x = -6x
-9 - -5 = -4
So, the answer is 2x^2 - 6x - 4
Hope this helps!