Question

Solve by using substitution
-7x-2y=-13   and   x-2y=11

Answer 1

`\left \{ {{-7x-2y=-13} \atop {x-2y=11}} \right. \\\\ \left \{ {{-7x-2y=-13} \atop {x=11+2y}} \right.\\\\ Substitute\ second\ equation\ into\ the\ first\ one:\\\\ -7(11+2y)-2y=-13\\ -77-14y-2y=-13\\ -77-16y=-13\ \ \ |Add\ 77\\ -16y= 64\ \ \ |Divide\ by\ -16\\ y=-4\\\\x=11+2y=11+2*(-4)=11-8=3\\\\ \left \{ {{y=-4} \atop {x=3}} \right.`