A basin can be filled with water from three taps. The first tap alone would fill the basin in 3 hours, the second in 6 hours, and the third in 12 hours. How long will it take to fill the basin if all three taps are turned on?
The pipes fill $\frac{1}{3}, \frac{1}{6}$, and $\frac{1}{12}$ of the tank in 1 hour. Therefore, if $x$ represents the time required to fill the entire tank, we can write the following equation:

$$
x \cdot\left(\frac{1}{3}+\frac{1}{6}+\frac{1}{12}\right)=1
$$

From this, the solution $\frac{12}{7}$ hours is obtained.