Final answer:
The cost to border the outside of the rectangular swimming pool using 1-yard square tiles that cost $4 each is (4x-10) * $4.
Step-by-step explanation:
To border the outside of the rectangular swimming pool, we need to find the measurement of its perimeter.
The width of the pool is 5 yards less than its length, so the width can be written as (x-5) yards.
The perimeter of the pool is the sum of all four sides, which is 2 times the length plus 2 times the width.
Therefore, the perimeter of the pool is 2x + 2(x-5) = 4x - 10 yards.
To calculate the cost of bordering the pool with 1-yard square tiles, we need to multiply the perimeter (4x-10) by the cost of each tile ($4). So, the total cost is (4x-10) * $4.
Therefore, the cost to border the outside of the pool is (4x-10) * $4.