2 Answers

Chiurox · Answer 1 · 2021-04-11T09:29:09+0000

Answer:

D.
x=-5,y=(5)/(4)

Explanation:

$\begin{bmatrix}5x+4y=-20\\ 5x+12y=-10\end{bmatrix}$

Subtract Equation 2 - Equation 1:

$5x+12y=-10\\-\\\underline{5x+4y=-20}\\8y=10$

Divide both sides by 8:

(8y)/(8)=(10)/(8)

y=(5)/(4)

Substitute
y=(5)/(4) into Equation 1:

5x+4y=-20

5x+4* (5)/(4)=-20

5x+5=-20

Subtract 5 from both sides:

5x+5-5=-20-5

5x=-25

Divide both sides by 5:

(5x)/(5)=(-25)/(5)

x=-5

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