Question

How do you solve by substitution `y=x+1` and `2x+y=7`?

Answer 1

`color(blue)(y=x+1`
`2x+color(blue)y=7`
`2x+color(blue)(x+1)=7`
`3x+1=7`
`3x=7-1=6` (we substract `1` on each side )
`color(red)x=6/3=color(red)2` (we divide by `3` on each side )

Now that we have `color(red)x`, we can find `color(blue)y` :
`color(blue)y=color(red)x+1=color(red)2+1=color(blue)3`