Question 21
In a park, there is a viewing trail that was paved with identical regular pentagonal stone bricks such that one side of a brick is connected to one side of another brick, as shown in the diagram. The gardener plans to make fences to each side of these stone bricks that are not in contact with the other stone bricks with a wooden board. If a total of 2021 wooden boards are needed to pave this trail, how many stone bricks are used?
