How do you solve $5 m - 4 n = 11$ $5m - 4n = 11$ and $3 m = n + 15$ $3m = n + 15$ using substitution?

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Answer 1 · 2018-05-01T11:00:38

$m = 7$ $m = 7$

$n = 6$ $n = 6$

$5 m - 4 n = 11$ $5m - 4n = 11$ ⇒ EQN 1

$3 m = n + 15$ $3m = n + 15$ ⇒ EQN 2

$3 m - 15 = n$ $3m - 15 = n$ ⇒EQN 3

Substitute EQN 3 into EQN 1

⇒ $5 m - 4 \cdot (3 m - 15) = 11$ $5m - 4*(3m-15) = 11$

⇒ $5 m - 12 m + 60 = 11$ $5m - 12m + 60 = 11$

⇒ $- 7 m = - 49$ $-7m = -49$

⇒ $m = 7$ $m = 7$

When $m = 7$ $m=7$ ,

⇒ $3 (7) = n + 15$ $3(7) = n + 15$

⇒ $n = 6$ $n = 6$

Check if the answers are correctly calculated.

$5 (7) - 4 (6) = 11$ $5(7) - 4(6) = 11$ √

$3 (7) = 6 + 15$ $3(7) = 6 + 15$ √

How do you solve 5m−4n=115m - 4n = 11 and 3m=n+153m = n + 15 using substitution?