The area of nathan's rug is 15 square ft. the longer side measures 5 ft. what is its perimeter?

To find the perimeter of the rug, we need to find the measurement of both sides of the rug. 

We will first use the information that we have, which is the area of the rug.
using the formula for Area 
15= 5 × x
The solution of the formula for area gives us the measurement  of the second side which is  x=3

Using this information in the formula for perimeter (which is to simply ADD all the sides)
we get:
5+3+5+3 = 16 ft.
(The perimeter does not get a "square" on its measurements. )