Answer:
6
Explanation:
7x + 3(-x + 6) = 42
use distributive property
7x + -3x + 18 = 42
positive + negative = negative
7x - 3x + 18 = 42
combine like terms
4x + 18 = 42
subtract 18 from both sides
4x + 18 - 18 = 42 - 18
18 is canceled out on the left side
4x + 0 = 24
4x = 24
divide both sides by 4
4x ÷ 4 = 24 ÷ 4
1x = 6
x = 6