Solve this system by elimination

-2x = -18 - 4y
18x + 78 = -24y

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I'll refer to the equations using capital letters:

A) -2x = -18 - 4y
B) 18x + 78 = -24y

Solve A for x giving C.


C) x = 9 + 2y

Substitute C in B and solve for y.

18(9 + 2y) + 78 = -24y

162 + 36y + 78 = -24y

240 = -60y

y = -240/60 = -4

Substitute Y in C to find x.

x = 9 + 2(-4)
x = 9 - 8
x = 1

Solution is x = 1, y = -4.