Question

solve using substitution.
$x + 9y = -15$
$-8x - 6y = -12$
(□, □)

Explanation:

Step1: Solve first equation for x

From \( x + 9y = -15 \), we get \( x = -15 - 9y \).

Step2: Substitute x into second equation

Substitute \( x = -15 - 9y \) into \( -8x - 6y = -12 \):
\[

$$\begin{align*} -8(-15 - 9y) - 6y &= -12\\ 120 + 72y - 6y &= -12\\ 120 + 66y &= -12 \end{align*}$$

\]

Step3: Solve for y

Subtract 120 from both sides: \( 66y = -12 - 120 = -132 \)
Divide by 66: \( y = \frac{-132}{66} = -2 \)

Step4: Substitute y back to find x

Substitute \( y = -2 \) into \( x = -15 - 9y \):
\( x = -15 - 9(-2) = -15 + 18 = 3 \)

Answer:

\( (3, -2) \)