n = - 7
distribute the brackets on the right side of the equation and simplify
- 21 = - 3n - 12 + 6n + 12
- 21 = 3n
divide both sides by 3
[tex]\frac{- 21}{3}[/tex] = n ⇒ n = - 7
-21 = -3(n + 4) - 6(-n - 2)
-21 = -3n - 12 + 6n + 12 distributed the -3 and the -6 on the right side
-21 = 3n added like terms (-3n + 6n) and (-12 + 12)
[tex]\frac{-21}{3} = \frac{3n}{3}[/tex]
-7 = n
Answer: n = -7
