# Systems of equations

• Dec 14th 2010, 05:00 PM
simoonlu
Systems of equations
I think I'm doing the steps right but I'm not turning out with the right answer.. ): help?

$2a-7b=-12 and -a+4b=7$

Substituting method is the way im doing it.
• Dec 14th 2010, 05:02 PM
dwsmith
$2a-7b=-12$

$-a+4b=7\Rightarrow a=4b-7$

$2(4b-7)-7b=-12$

$8b-14-7b=-12$

$b=2$