Final answer:
The perimeter of a regular pentagon with side length s is 5 times the length of one side, therefore P = 5s.
Step-by-step explanation:
The perimeter, P, of a regular pentagon with side length, s, can be found by multiplying the length of one side by the number of sides in the pentagon. Since a pentagon has 5 sides, the formula to calculate the perimeter is P = 5s. This formula derives from understanding that perimeter is the total length around a 2D shape - similar to how the perimeter of a square is 4 times the length of one side because there are 4 sides in a square.