Question

solve 4x-4y=-16; x-2y=-12 by using substitution

Answer 1

$\left\{\begin{array}{ccc}4x-4y=-16\\x-2y=-12\end{array}\right\\\\\left\{\begin{array}{ccc}4x-4y=-16\\x=2y-12\end{array}\right\\\\substitution:\\\\4(2y-12)-4y=-16\\8y-48-4y=-16\\4y=-16+48\\4y=32\ \ \ \ /:4\\y=8\\\\x=2\cdot8-12=16-12=4\\\\Solution:x=4\ and\ y=8$