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. 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 [tex]\( t \)[/tex], the time, in hours, since leaving the airport?

A. [tex]\( d = 825 - 165t \)[/tex]
B. [tex]\( d = 825 - 330t \)[/tex]
C. [tex]\( d = 825 + 165t \)[/tex]
D. [tex]\( d = 825 + 330t \)[/tex]



Answer :

Let's break down the problem step-by-step to understand which equation represents the remaining distance to the destination in terms of [tex]\( t \)[/tex], the time in hours since leaving the airport.

1. Total Distance:
The plane needs to travel a total distance of 825 miles.

2. Distance Covered in First Hour:
After one hour, the pilot announces that the plane is 495 miles away from the destination. This means the plane has covered:
[tex]\[ 825 \text{ miles} - 495 \text{ miles} = 330 \text{ miles} \][/tex]
So, in the first hour, the plane covers 330 miles.

3. Distance Covered in Another Hour:
After the second hour, the plane begins its half-hour descent for the final 165 miles. This means for the two hours before the descent, the plane covers:
[tex]\[ 825 \text{ miles} - 165 \text{ miles} = 660 \text{ miles} \][/tex]
Since this 660 miles is covered in 2 hours, the plane’s speed remains constant:
[tex]\[ \frac{660 \text{ miles}}{2 \text{ hours}} = 330 \text{ miles per hour} \][/tex]
Thus, in each hour, the plane covers 330 miles.

4. Equation for Remaining Distance:
To find an equation for the remaining distance, [tex]\( d \)[/tex], in terms of [tex]\( t \)[/tex], the time in hours since leaving the airport, note that every hour the plane travels 330 miles. Therefore, after [tex]\( t \)[/tex] hours:
[tex]\[ \text{Distance Covered} = 330t \text{ miles} \][/tex]
Thus, the remaining distance to the destination is:
[tex]\[ d = 825 \text{ miles} - 330t \text{ miles} \][/tex]

Therefore, the equation that represents the remaining distance to the destination in terms of [tex]\( t \)[/tex] hours is:
[tex]\[ d = 825 - 330t \][/tex]

Thus, the correct equation from the given options is:
[tex]\[ d = 825 - 330t \][/tex]