Answer:
1200 miles.
Step-by-step explanation:
Let d represent one way distance.
We have been given that a plane averaged 800 mph on a trip going east, but only 400 mph on the return trip.
[tex]\text{Time}=\frac{\text{Distance}}{\text{Speed}}[/tex]
The time taken while going east would be [tex]\frac{d}{800}[/tex].
The time taken while returning back would be [tex]\frac{d}{400}[/tex].
Since the total flying time in both directions was 4.5 hr, so we will equate sum of both times with 4.5 as:
[tex]\frac{d}{800}+\frac{d}{400}=4.5[/tex]
Make a common denominator:
[tex]\frac{d}{800}+\frac{d*2}{400*2}=4.5[/tex]
[tex]\frac{d}{800}+\frac{2d}{800}=4.5[/tex]
[tex]\frac{d+2d}{800}=4.5[/tex]
[tex]\frac{3d}{800}=4.5[/tex]
[tex]\frac{3d}{800}\times \frac{800}{3}=4.5\times \frac{800}{3}[/tex]
[tex]d=1.5\times \frac{800}{1}[/tex]
[tex]d=1200[/tex]
Therefore, the one-way distance was 1200 miles.