A garden tap fills $\frac{3}{4}$ of a tub in 9 minutes. How long does it take to fill the whole tub?

Explanation

1. 01

   $\frac{3}{4}$ of the tub takes 9 minutes, so $\frac{1}{4}$ takes 3 minutes.

2. 02

   The whole tub takes $4 \times 3 = 12$ minutes.