[tex]\begin{gathered} n\text{ = 6} \\ x\text{ = -13} \end{gathered}[/tex]
Explanation:
[tex]\begin{gathered} 20)\text{ -15 + n = - 9} \\ \text{Subtraction inverse is addition} \\ \text{The inverse of -15 is + 15} \\ \text{Add the inverse to both sides:} \\ -15\text{ + 15 + n = - 9 + 15} \\ n\text{ = 6} \end{gathered}[/tex][tex]\begin{gathered} 21)\text{ -104 = 8x} \\ 8\text{ is multiplied by x} \\ \text{Inverse of multiplication is division} \\ \text{divide both sides by 8:} \\ \frac{-104}{8}=\frac{8x}{8} \\ x\text{ = -13} \end{gathered}[/tex]
