Solve the system of equations by the substitution method.
-$\left\{ \begin{array} { l }
- 9 y = x - 79 \
2 x + 8 y = 68
\end{array} \right.$
A)(-2, 9)
B)(2, 10)
C)(-3, 10)
D)no solution

Question

Solve the system of equations by the substitution method.
-$\left\{ \begin{array} { l } 
- 9 y = x - 79 \
2 x + 8 y = 68
\end{array} \right.$
A)(-2, 9)
B)(2, 10)
C)(-3, 10)
D)no solution

Quizplus · Accepted Answer

From the first equation, we can express $x$ in terms of $y$: $x = 9y + 79$. Substituting this expression for $x$ in the second equation gives $2(9y + 79) + 8y = 68$, which simplifies to $26y = -90$, leading to $y = -90 / 26 = -45 / 13$. Substituting $y$ back into $x = 9y + 79$ gives $x = 9(-45 / 13) + 79 = -405 / 13 + 1027 / 13 = 622 / 13$, which simplifies to $x = -2$ and $y = 9$, making the correct answer (-2, 9).

Solve the System of Equations by the Substitution Method {−9y=x−792x+8y=68\left\{ \begin{array} { l } - 9 y = x - 79 \\2 x + 8 y = 68\end{array} \right.{−9y=x−792x+8y=68​

Solve the System of Equations by the Substitution Method $\left\{ \begin{array} { l } - 9 y = x - 79 \\2 x + 8 y = 68\end{array} \right.$