What's substitution for: X=y-7 X+8y=2

1 answer:

4 0

$\left \{ {{x=y-7} \atop {x+8y=2}} \right. \\\\
substitute\ x=y-7\ into \ the\ second\ equation\\\\
y-7+8y=2\\\\
9y-7=2\ \ \ | add\ 7\\\\
9y=9\ \ \ | divide\ by\ 9\\\\
y=1\\\\x=y-7=1-7=-6$

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