Solve using any method.
$$\left\{ \begin{aligned}
7 x - 9 y & = 3 \
y & = x - 4
\end{aligned} \right.$$
A) $( - 4 , - 8 )$
B) $\left( 7 , \frac { 66 } { 7 } \right)$
C) $\left( - \frac { 39 } { 2 } , \frac { 31 } { 2 } \right)$
D) $\left( \frac { 33 } { 2 } , \frac { 25 } { 2 } \right)$
E) inconsistent

Question

Quizplus · Accepted Answer

Substitute $y=x-4$ into the first equation to get $7x-9(x-4)=3$. Simplify to get $16x=39$, so $x=\frac{39}{16}$. Substitute this value back into $y=x-4$ to get $y=\frac{25}{2}$. Therefore the solution is $\left(\frac{33}{2}, \frac{25}{2}\right)$. The answer is choice D.

Solve Using Any Method {7x−9y=3y=x−4\left\{ \begin{aligned}7 x - 9 y & = 3 \\y & = x - 4\end{aligned} \right.{7x−9yy​=3=x−4​

Solve Using Any Method $\left\{ \begin{aligned}7 x - 9 y & = 3 \\y & = x - 4\end{aligned} \right.$