# algebra

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Solve using the substitution method 6x-3y=18, 6x+3y=-12

• algebra -

Substitution:
Rewrite each as:
6x=3y+18
6x=-12-3y
Since they are both 6x, then
3y+18=-12-3y
=>
6y=-30
y=-5
and
x=(3*(-5)+18)/6=1/2

By elimination (easier in this case)
6x-3y + 6x+3y = 18 -12
12x=6
x=1/2
-3y=18-6*(1/2)
y=-5

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