### Home > CCA2 > Chapter 7 > Lesson 7.1.2 > Problem7-23

7-23.

Solve the system of equations shown below.
$x + y + z = 40\\y=x−5\\ x=2z$

Use substitution to solve.

If $x=2z$, then $y=2z−5$.

Now that you have expressions for both $x\ \text{and}\ y$ in terms of $z$, substitute them into the first equation and solve for $z$.
Then solve for $x\ \text{and}\ y$.