How do you solve the following system?: x +7y = 3 , 12x + 3y = -2

Jul 9, 2018

Multiply the first equation by 12

$12 x + 84 y = 36$

We have $12 x$ in both equations so subtract the second equation from the first

$12 x + 84 y = 36$
$12 x + 3 y = - 2$

$81 y = 38$

$y = \frac{38}{81}$

Substitute this into equation two

$12 x + 3 \times \frac{38}{81} = - 2$

$12 x + \frac{38}{27} = - 2$

$12 x = - \frac{92}{27}$

$x = - \frac{23}{81}$