3x+9y=45
y=-x-1. what is the answer

Equation 1)  -3x + 9y = 45
Equation 2)  y = -x - 1

Add x to both sides on equation 2.

2)  x + y = -1
1)  -3x + 9y = 45

Multiply ALL of equation 2 by 3.

2)  3(x + y = -1)

Simplify.

2)  3x + 3y = -3
1)  -3x + 9y = 45

Add equations together.

12y = 42

Divide both sides with 12.

y = 3.5

Plug in 3.5 for y in the first equation.

-3x + 9y = 45

-3x + 9(3.5) = 45

Simplify.

-3x + 31.5 = 45

Subtract 31.5 from both sides.

-3x = 45 - 31.5

Simplify.

-3x = 13.5

Divide both sides by -3.

x = -4.5

(-4.5, 3.5)

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