Answer: OK two different answers.
If the dimensions of the pool are 100 × 30, and the sidewalk is outside that, the area of the sidewalk is 1251 square feet.
If the outside dimensions of the sidewalk are 100 × 30, and the pool is inside that, the area of the sidewalk is 1089 square feet.
Step-by-step explanation: Solution #1: Sidewalk outside 100×30 pool.
The sidewalk is 4 1/2 feet wide, so twice as wide all together.
The outside ends of the sidewalk are added to the pool dimensions.
100 + 9 = 109 30 + 9 = 39
The overall area: Multiply 109 × 39 = 4251 ft²
Find the area of the pool 100 × 30 = 3000 ft²
Subtract the area of the pool from the overall area 3000 - 2451 = 1251
1251 square feet is the area of this sidewalk
Solution #2: Pool inside 100×30 sidewalk.
The sidewalk is 4 1/2 ft wide so the pool will be 9 feet shorter in length and width,
100- 9 = 91 and 30 - 9 = 21 The area of this pool is 91 × 21 = 1911 ft²
The overall area is 100 × 30 = 3000 ft²
Subtract the pool's area from the overall area
3000 - 1911 = 1089
The area of this sidewalk is 1089 square feet