How do you solve $5 m + n = 43$ $5m+n=43$ and $m - 2 n = 13$ $m-2n=13$ using substitution?

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Answer 1 · 2018-04-03T22:18:22

$m = 9$ $m = 9$
$n = - 2$ $n=-2$

$5 m + n = 43 \Rightarrow n = 43 - 5 m$ $5m + n = 43 => n = 43-5m$

$m - 2 (43 - 5 m) = 13$ $m-2(43-5m )=13$
$m - 86 + 10 m = 13$ $m-86+10m =13$
$11 m - 86 = 13$ $11m-86=13$
$11 m = 99$ $11m=99$

$m = \frac{99}{11} = 9$ $m=99/11=9$

$n = 43 - 5 m$ $n = 43-5m$
$n = 43 - 5 \times 9 = - 2$ $n = 43-5 times 9 =-2$

Double check:

$5 \times 9 + (- 2) = 43$ $5 times 9 + (- 2) = 43$
$9 - 2 \times (- 2) = 9 + 4 = 13$ $9-2times(-2)=9+4 = 13$

How do you solve 5m+n=435m+n=43 and m−2n=13m-2n=13 using substitution?