SOLUTION: 5a-b=12 7a-3b=20 find a and b.

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Question 699550: 5a-b=12
7a-3b=20
find a and b.

Answer by Stitch(470)   (Show Source): You can put this solution on YOUR website!
Given: and
Set both equations equal to zero


Notice that you can make both equations contain -3B if you multiply the first equation by 3.

Simplify

Now both equations have a -3B in them.
Since both equations are equal to zero, you can set them equal to each other.

Add 3B to both sides

Subtract 7A from both sides

Add 36 to both sides

Divide both sides by 8

Now plug 2 into on of the given equations for A. Then solve for B



Subtract 10 from btoh sides

Divide both sides by -1

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