4th grade
posted by Kiara .
Mr. Kimball has a swimming pool that measures 20 feet long by 15 feet wide. He is adding a walkway around the pool that is 3 feet wide all around. What will be the perimeter of the walkway?

20 + 6 = 26
15 + 6 = 21
P = (2 * 26) + (2 * 21)
P = ? 
Can it be: (2*20) + (2*15) + (4*3)

Draw this out on a piece of graph paper. Then you'll see which answer is correct.

But wouldn't it be (2*23) + (2*18) than?

The walk goes all the way around the pool.
The pool is 20 feet long and has 3 feet of walk on one end and 3 feet of walk on the other end. Thus the length of the walk on each side is 26 feet.
The pool is 15 feet wide and has 3 feet of walk on each side. Thus the total length of the walk on each side is 21 feet.