Final answer:
The maximum allowable square footage of the office building is 10,800 square feet.
Step-by-step explanation:
To find the maximum allowable square footage of the office building, we need to consider the setbacks required by the local ordinance. The ordinance requires a 20-foot rear setback, a 20-foot front setback, and a 10-foot side setback.
Since the lot measures 100' x 200', we subtract the setbacks from each side to determine the available space for building. The rear setback reduces the depth of the lot by 20 feet, the front setback reduces the depth by another 20 feet, and the side setback reduces the width by 10 feet on both sides.
So the dimensions for building the office building would be 60' x 180'. The maximum allowable square footage is found by multiplying the length and the width: 60' x 180' = 10,800 square feet.