Simplify (4x^3 + 3x^2 − 7x) − (7x^3 − 5x^2).

thank you

First remove the brackets:

4x^3+3x^2-7x-7x^3+5x^2

Then add like terms (4x^3+(-7x^3) and so on) and you get:

-3x^3+8x^2-7x