Question

Can someone explain me this, plz!
Solve the system by substitution.
x+7y=-2
y=-3x+34
Thx!!

Answer 1

plug y into x, so we have
x+7(-3x+34)=-2
now solve for x
x-21x+238=-2
-20x=-240
x=12

plug x back into one of the equation to get y

Answer 2

x+7y=-2
y=-3x+34
--
x=-2-7y
*
--
*
y=-3(-2-7y)+34
--
*
y=6+21y+34
-20y=40
y=-2
and x+7(-2)=-2
x-14=-2
x=12

***
x=12
y=-2

Answer 3

resolves?

Answer 4

Thx!!