# It takes Noah 3 hours to paint one side of a fence. It takes Gilberto 5 hours. How long would it take them if they worked together?

Mar 12, 2017

I tried this but check it.

#### Explanation:

Let us say that the rates at which each one paints the surface (of area $1$ for example) are:
$\frac{1}{3}$ and $\frac{1}{5}$ to paint the same surface so together they will need a time $t$:
$\frac{1}{3} t + \frac{1}{5} t = 1$
rearranging:
$5 t + 3 t = 15$
$8 t = 15$
$t = \frac{15}{8} = 1.875$ less than 2 hours.