SOLUTION: solve by the substitution method 4m+n=17 m-2n=20

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Question 234066: solve by the substitution method
4m+n=17
m-2n=20
Answer by rfer(16322) About Me  (Show Source):
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m-2n=20
m=2n+20
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4m+n=17
4(2n+20)+n=17
8n+80+n=17
9n=-63
n=-7
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m-2(-7)=20
m+14=20
m=6
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4(6)-7=17