# Sarah is 25 years older than her son Gavin, In ten years, Sarah will be twice Gavin's age, How old are Sarah and Gavin now?

Dec 12, 2016

I found:
Gavin $15$
Sara $40$

#### Explanation:

Call the ages of Sara $s$ and Gavin $g$, we get:
$s = g + 25$
$s + 10 = 2 \left(g + 10\right)$
substitute the first into the second for $s$:
$\left(\textcolor{red}{g + 25}\right) + 10 = 2 g + 20$
rearrange:
$g = 15$
back into the first:
$s = 15 + 25 = 40$