I am have trouble figuring out polynomial

Question

(6x^2-7x^3)-(2x^2-x^3)

 

I have the answer but can not figure out how they got it.

 

The answer is -6x^3+4x^2

Answer 1

-7x³ + 6x² - (2x² - x³)

 

First, distribute the minus sign across the terms in the second set of parentheses:

 

-7x³ + 6x² - 2x² + x³

 

Now gather like terms:

 

(-7x³ + x³) + (6x² - 2x²)

 

Now add/subtract the like terms:

 

-6x³ + 4x²