Question

How do you solve by substitution `-x+y=5` and `y=-3x+1`?

Answer 1

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

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

Using [5] substitute `(-1)` of `x` in [1]
[6]`color(white)("XXXX")` `-(-1) + y = 5`
Simplifying
[7]`color(white)("XXXX")` `y=4`

Solution is `(x,y) = (-1,4)`