Question

Daniel is on an airplane flying to a destination 825 miles away. After one hour, the pilot announces that the plane is 495 miles away from its destination airport. In another hour, the pilot announces that the plane will begin its half-hour descent for the final 165 miles.

Which equation represents the remaining distance, in miles, to the destination in terms of t, the time, in hours, since leaving the airport?

d = 825 – 165t
d = 825 – 330t
d = 825 + 165t
d = 825 + 330t

Answer 1

d = 825 − 330t

Reason: In the first hour the plane goes from 825 to 495 miles away, a decrease of 330 miles in 1 hour, so the rate is 330 mi/hr. Thus d = 825 − 330t (gives 495 at t=1 and 165 at t=2).