Question

How do you solve the system using elimination `x=-4y` and `3x+5y=-11`?

Answer 1

Given
[1]`color(white)("XXXX")` `x=-4y`
[2]`color(white)("XXXX")` `3x+5y = -11`

Using [1] substitute `(-4y)` for all occurrences of `x` in [2]
[3]`color(white)("XXXX")` `3(-4y) +5y = -11`
Simplifying
[4]`color(white)("XXXX")` `-7y = -11`
[5]`color(white)("XXXX")` `y = 11/7`

Substituting `11/7` for `y` back into [1]
[6]`color(white)("XXXX")` `x = -4(11/7) = 1 44/7`

`(x,y) = (-44/7, 11/7)`