Apply the distributive property:
7x + (3x+3. -2) - 4x + 8
Multiply 3 by -2 to get -6:
7x + (3x - 6) - 4x + 8
Remove unnecessary parentheses:
7x + 3x - 6 - 4x + 8
Add 7x and 3x to get 10x:
10x - 6 - 4x + 8
Subtract 4x from 10x to get 6x:
6x - 6 + 8
Add -6 and 8 to get 2:
6x + 2