SOLUTION: Solve with the substitution method. 7m + n=12 m-8n = 75 What is the ordered pair?

Question 452069: Solve with the substitution method.
7m + n=12
m-8n = 75
What is the ordered pair?
Answer by AHBK(13) (Show Source): You can put this solution on YOUR website!
ok we have 7m+n=12 and m-8n=75 .
you want to solve it by substitution method so here we go...
we have m-8n=75,
so m=8n+75,
then we substitute the value of m in the equation (7m+n=12)
we get : 7(8n+75)+n=12. we expand.
we get : 56n+525+n=12,
so , 57n+525=12
57n=12-525, 57n= -513,
so n=-(513/57) , then n= -9
then substitute the value of n in any equation you want lets go with (7m+n=12) not necessarily this equation you can pick the other one you will get the same solution.
7m+n=12, 7m+(-9)=12 , 7m-9=12, 7m=12+9 ,
so 7m=21,
then m= 21/7
m=3
and solution is m=3 and n= -9
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