SOLUTION: 3r-7s=-28 7r+3s=70

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Question 197240: 3r-7s=-28
7r+3s=70
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
3r-7s=-28 MULTIPLY BY 3
7r+3s=70 MULTIPLY BY 7 & ADD
9r-21s=-84
49r+21s=490
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58r=406
r=406/58
r=7 ans.
3*7-7s=-28
21-7s=-28
-7s=-28-21
-7s=-49
s=-49/-7
s=7 ans.
Proof:
7*7+3*7=70
49+21=70
70=70