SOLUTION: I need to find the intersection of two lines 4x+7y= 76 3x-9y= -57 I have tried multiplying them to cancel out X but I cannot find the correct number when solving for y. I go

Question 843798: I need to find the intersection of two lines
4x+7y= 76
3x-9y= -57
I have tried multiplying them to cancel out X but I cannot find the correct number when solving for y. I got 30.4 but then when I plugged it in I got 72.2 for one and 34.2 for the other, they are supposed to be equal.
Answer by 1335(25) (Show Source): You can put this solution on YOUR website!
Instead of multiplying, try using the linear combination method.
Multiply the first equation by 9 and the second equation by 7.
First equation: 36x+63y=684
Second equation: 21x-63y=-399
Now add the two equations together. The Ys will cancel.
57x=285
Now solve for x.
x=5
Plug 5 in for x into either original equation
36(5)+63y=684
Now just solve for y.
180+63y=684
63y=504
y=8
x=5 and y=8
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