Final answer:
The perimeter of the rectangular garden is calculated by adding up all the sides. Josh needs to purchase 42 feet of fencing.
Step-by-step explanation:
To find the amount of fencing Josh needs to purchase, we need to calculate the perimeter of the rectangular garden. The perimeter of a rectangle can be found by adding up all the sides of the rectangle.
Given that the length of the garden is 6 feet and the width is 15 feet, we can calculate the perimeter as follows:
Perimeter = 2 * (Length + Width)
Perimeter = 2 * (6 + 15)
Perimeter = 2 * 21
Perimeter = 42 feet
Therefore, Josh needs to purchase 42 feet of fencing.