Find all rational numbers each of which is equal to its reciprocal.

What is the value of

Find the value of

A bus shuttles between two neigbouring towns every two hours. It starts from 8 AM in the morning and the last trip is at 6 PM. On one day the driver observed that the first trip had 30 passengers and each subsequent trip had one passenger less than the previous trip. How many passengers travelled on that day?

How many rational numbers are there between 0 and 1 for which q < p?