# Question #31638

Dec 5, 2017

The sum is 27 years of age.

#### Explanation:

We know that $v + 2 c = 39$ and $2 v + c = 42$

We use elimination to solve this.
We make sure that v in both equations share the same coefficient.
$v + 2 c = 39$ becomes
$2 v + 4 c = 78$ by multiplying the equation by 2.

We now subtract the equations.

$2 v + 4 c = 78$
$2 v + c = 42$
$3 c = 36$
$c = 12$
Plug this to one of the equations to get v=15.