Daniel can encode a paper in $5$ hours and together he and Dennis can encode it in $2$ hours, how long would it take Dennis to encode the same paper alone?

$\frac{1}{5}+\frac{1}{n}=\frac{1}{2}$

$2n+10=5n$

$10=3n$

$n=\frac{10}{3}$

$n=3{\displaystyle \frac{1}{3}}$