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

color(blue)(y=x+1
$2 x + \textcolor{b l u e}{y} = 7$
$2 x + \textcolor{b l u e}{x + 1} = 7$
$3 x + 1 = 7$
$3 x = 7 - 1 = 6$ (we substract $1$ on each side )
$\textcolor{red}{x} = \frac{6}{3} = \textcolor{red}{2}$ (we divide by $3$ on each side )
Now that we have $\textcolor{red}{x}$, we can find $\textcolor{b l u e}{y}$ :
$\textcolor{b l u e}{y} = \textcolor{red}{x} + 1 = \textcolor{red}{2} + 1 = \textcolor{b l u e}{3}$