How do you solve $4x+5y=12$ and $-9+y=71$ using substitution?

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Answer 1 · 2018-05-13T17:52:43

$x = -97 and y=80$

Substitution will be a good method in this case because there is a single $y$ in the second equation.

$y = 71+9=80$

$4x +5y = 12$

$4x +5(80) = 12$

$4x = 12-400$

$4x = -388$

$x =-97$

Check for $x=-97 and y=80$

$4(-97) +5(80)=12$

How do you solve 4x+5y=124x+5y=12 and -9+y=71-9+y=71 using substitution?