SOLUTION: solve by subsititution method 9m+n=77 m-3n=21

Question 221134: solve by subsititution method 9m+n=77 m-3n=21
Found 2 solutions by drj, MathTherapy:
Answer by drj(1380) (Show Source): You can put this solution on YOUR website!
Solve by substitution method

9m+n=77
m-3n=21

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION

Solve:
We'll use substitution. After moving 1*n to the right, we get:
, or . Substitute that
into another equation:
and simplify: So, we know that n=-4. Since , m=9.

Answer: .

I hope the above steps and explanation were helpful.

For Step-By-Step videos on Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry please visit http://www.FreedomUniversity.TV/courses/Trigonometry.

Also, good luck in your studies and contact me at john@e-liteworks.com for your future math needs.

Respectfully,
Dr J
Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!
solve by subsititution method 9m+n=77 m-3n=21

9m + n = 77 ------ (i)
m - 3n = 21 ------(ii)

m = 21 + 3n ----- Solving for m in eq (ii)

9(21 + 3n) + n = 77 ------ Substituting 21 + 3n for m in eq (i)

189 + 27n + n = 77

28n = - 112

n = =

m - 3(-4) = 21 ----- Substituting - 4 for n in eq (ii)

m + 12 = 21

m = 21 - 12 =
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