Question

Which ordered triple is a solution of the following linear system?:

3n = -18
3m - 2n + 4p = 12
2m - 4n = 16

Answer 1

$3n = -18\\ 3m - 2n + 4p = 12\\ 2m - 4n = 16\\\\ n=-6\\ 3m-2n+4p=12\\ m-2n=8\\\\ 3m-2\cdot(-6)+4p=12\\ m-2\cdot(-6)=8\\\\ 3m+12+4p=12\\ m+12=8\\\\ 3m=-4p\\ m=-4\\\\ 3\cdot(-4)=-4p\\ -4p=-12\\ p=3\\\\ \boxed{(m,n,p)=(-4,-6,3)}$