Given:
The length of rectangular swimming pool is L = 90 feet.
The width of rectangular swimming pool is w = 80 feet.
The dimnsion of tile is 1 foot by 1 foot.
Step-by-step explanation:
The formula for the perimeter of rectangular swimming pool is,

Substitute the values in the formula to determine the perimeter of rectangular swimming pool.

So 340 tiles surrounds the boundary of rectangular swimming pool. There are 4 corners of rectangular swimming pool.
The total number of tiles required for rectangular swimming pool is,

Answer: 344