Question

How do you solve the system by substitution 6x+2y=-26 x-6y=21

Answer 1

$\begin{cases} 6x+2y=-26 \ \ / *3 \\ x-6y=21 \end{cases}\\ \\\begin{cases} 18x+6y=-78 \\ x-6y=21 \end{cases}\\ \\+ \---------\\19x= -57 \ \ /:19\\ \\x=-\frac{57}{19}\\ \\x=-3$
 
$x-6y=21\\ \\ -3-6y=21 \ \ | 3\\ \\ -3+3-6y=21+3\\ \\-6y=24 \ \ /:(-6)\\ \\y=-\frac{24}{6} \\ \\ y=-4\\ \\\begin{cases} x=-3 \\ y=-4 \end{cases}$