Ben drinks 3 1/2 liters of tea every 40 minutes.
This means that he would drink 1 3/4 of tea every 20 minutes (divide both sides by 2).
Now, let's multiply each side by 3.
1.75 * 3 = 5.25 (aka 5 1/4)
20 * 3 = 60 minutes (an hour)
He drinks 5 1/4 liters of tea in one hour.
