Question

How do you solve `x+y = 4` and `y=x+4`?

Answer 1

The solution for the system of equations is
`color(blue)(x=0,y=4`

Explanation:

`x+y=4`
`x=color(blue)(4-y`....equation `(1)`

`y=x+4`.....equation `(2)`

Solving by substitution:

Substituting equation `1` in equation `2` to find `y`
`y=x+4`
`y=4-y+4`
`2y=8`
`color(blue)(y=4`

Substitute `y` in equation `1` to find `x`
`x=4-y`
`x=4-4`
`color(blue)(x=0`