Answer:
Distance she walked from bus stop to aquarium = 0.5 miles
Explanation:
The aquarium is 2 1/2 miles from her hotel.

She walks 1/4 mile to the bus stop

She takes the bus for 1 3/4 miles

She walks from bus stop to aquarium
Distance she walked from bus stop to aquarium = 2.5 - 0.25 - 1.75 = 2.5 -2 = 0.5 miles
Distance she walked from bus stop to aquarium = 0.5 miles