Explanation

If 2 people can make 2 bicycles in 2 hours, then:

2 people can make 1 bicycle in 1 hour (since 2 bicycles in 2 hours means 1 bicycle per hour for 2 people).

In 6 hours, 2 people can make 6 bicycles.

To make 12 bicycles in 6 hours, you would need:

(12 bicycles / 6 bicycles) × 2 people = 4 people