Simplify the algebraic expression by combining like terms.

-x^2+5x

Step-by-step explanation:

Okay. Let us start by underlining those like terms:

7x^2 - 5x +10x  -8x^2

7x^2-8x^2     -5x+10x (I basically grouped the like terms together)

-x^2    +5x (I solved it in those groups)

-x^2+5x   (answer)

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.