SOLUTION: Solve by the elimination method. 7r-5s=-12 5r-7s=76 What is the solution of the system?

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Question 221974: Solve by the elimination method. 7r-5s=-12 5r-7s=76
What is the solution of the system?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
7r-5s=-12 multiply by -5
5r-7s=76 multiply by 7 & add.
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-35r+25s=60
35r-49s=532
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-24s=592
s=592/-24
s=-74/3 ans.
7r-5*-74/3=-12
7r+370/3=-12
7r=-12-370/3
7r=(-12*3-370)/3
7r=(-36+370)/3
7r=-406/3
r=(-406/3)/7
r=-406/21 ans.
Proof:
5*-406/21-7*-74/3=76
-2030/21+518/3=76
-2030/21+7*518/3*7=76
-2030/21+3626/21=76
1596/21=76
76=76