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Substituting to solve systems

-4x + 6y = -18 and y = -2x + 21

a) x = 6, y = 9
b) x = 9, y = 6
c) x = 3, y = 15
d) x = 15, y = 3

1 Answer

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Final answer:

To solve the system of equations -4x + 6y = -18 and y = -2x + 21, we can substitute the value of y from the second equation into the first equation. The solution to the system of equations is x = 9 and y = 3.

Step-by-step explanation:

To solve the system of equations -4x + 6y = -18 and y = -2x + 21, we can substitute the value of y from the second equation into the first equation.

Substituting y = -2x + 21 in -4x + 6y = -18, we get -4x + 6(-2x + 21) = -18.

Simplifying this equation, we have -4x - 12x + 126 = -18. Combining like terms, we get -16x + 126 = -18.

Further simplifying, we have -16x = -18 - 126, which gives -16x = -144. Finally, dividing both sides by -16, we get x = 9. Substituting this value of x back into y = -2x + 21, we get y = -2(9) + 21 = 3.

Therefore, the solution to the system of equations is x = 9 and y = 3.

User Bhoomika Patel
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