Working alone, pump A can empty a pool in 3 hours. Working

If pump A can empty pool in 3 hours
$$In\ 1\ hour\ it\ will\ empty\ \frac{1}{3}of\ the\ pool$$
If pump B can empty the pool in 2 hours,
$$In\ 1\ hour\ it\ will\ empty\ \frac{1}{2}of\ the\ pool$$
By working together their work rate per hour =
$$=\ \frac{1}{3}+\frac{1}{2}$$
$$=\frac{\left(2+3\right)}{6}=\ \frac{5}{6}of\ the\ pool\ per\ hour$$
1 hour = 60 minutes.
$$If\ the\ two\ pumps\ can\ empty\ \frac{5}{6}of\ the\ pool\ in\ 60\ \min utes,\ how\ many\ \min utes\ will\ it\ take\ for\ them\ to\ empty\ the\ whole\ pool\ completely.$$
$$\frac{5}{6}=60\ \min utes$$
$$1\ =\ x$$
$$\frac{5}{6}x\ =60\ \cdot\ 1$$
$$x\ =\ \frac{60}{\frac{5}{6}}$$
$$x=\frac{60\cdot6}{5}\ =\ \frac{360}{5}=72$$
Option A is CORRECT.