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18x-16y=-312 78x-16y=408

1 Answer

2 votes
elimination
multiply first equation by -1 and add to 2nd


-18x+16y=312
78x-16y=408 +
60x+0y=720

60x=720
divide both sides by 60
x=12

sub back

18x-16y=-312
18(12)-16y=-312
216-16y=-312
-16y=-528
divide both sides by -16
y=33


x=12
y=33
(x,y)
(12,33)
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