Question

Y-3x=2
y=-2x-8
how do i solve this by substitution

Answer 1

y-3x=2
y=-2x-8
-2x-8-3x=2
-5x-8=2 add 8 from both side
-5x=10 divided -5 both side
x=-2

Answer 2

`\left \{ {{y-3x=2} \atop {y=-2x-8}} \right. \\\\Substitute\ second\ equation to\ first:\\\\-2x-8-3x=2\\-2x-3x=2+8\\-5x=10\ \ \ \ \ \ |:-5\\x=-2\\\\y=-2\cdot(-2)-8\\y=4-8\\y=-4\\\\ \left \{ {{y=-4} \atop {x=-2}} \right.`