Solve the system by the addition method. $$\begin{array} { l }
7 x + 9 y = 128 \
3 x - 9 y = - 48
\end{array}$$
A) $( - 1,15 )$
B) $( 17,1 )$
C) $( 8,8 )$
D) $( 17,11 )$

Question

Solve the system by the addition method. $$\begin{array} { l } 
7 x + 9 y = 128 \
3 x - 9 y = - 48
\end{array}$$
A) $( - 1,15 )$
B) $( 17,1 )$
C) $( 8,8 )$
D) $( 17,11 )$

Quizplus · Accepted Answer

Adding the two equations directly eliminates $y$, giving $10x = 80$, so $x = 8$. Substituting $x = 8$ into one of the original equations to solve for $y$ gives $y = 8$. Therefore, the solution is $(8,8)$.

Solve the System by the Addition Method 7x+9y=1283x−9y=−48\begin{array} { l } 7 x + 9 y = 128 \\3 x - 9 y = - 48\end{array}7x+9y=1283x−9y=−48​

Solve the System by the Addition Method $\begin{array} { l } 7 x + 9 y = 128 \\3 x - 9 y = - 48\end{array}$