Solve by the substitution method.
-$$\begin{array} { l }
6 x + 9 y = 114 \
4 x - 4 y = - 4
\end{array}$$
A) No solution
B) $( 7,9 )$
C) $( 6,9 )$
D) $( 7,8 )$

Question

Solve by the substitution method.
-$$\begin{array} { l } 
6 x + 9 y = 114 \
4 x - 4 y = - 4
\end{array}$$
A) No solution
B) $( 7,9 )$
C) $( 6,9 )$
D) $( 7,8 )$

Quizplus · Accepted Answer

First, we isolate one variable in terms of the other in one of the equations. 
From the second equation, we have:
$$4x-4y=-4$$
$$4x=4y-4$$
$$x=y-1$$
We substitute this expression for x into the first equation:
$$6x+9y=114$$
$$6(y-1)+9y=114$$
$$15y=120$$
$$y=8$$
We can then substitute this value of y back into the expression for x:
$$x=y-1=7$$
Therefore, the solution is (7,8), and the answer is D.

Solve by the Substitution Method 6x+9y=1144x−4y=−4\begin{array} { l } 6 x + 9 y = 114 \\4 x - 4 y = - 4\end{array}6x+9y=1144x−4y=−4​

Solve by the Substitution Method $\begin{array} { l } 6 x + 9 y = 114 \\4 x - 4 y = - 4\end{array}$