Verified answer

2800 Miles.

To get travel time, you divide the distance by the mph (speed). mph is really miles divided by hours. So you have:

D is distance, S is speed and T is travel time.

D miles / S mph = T hours

or:

miles / (miles/hours) ------Multiply by hours/hours, which is 1:

(miles X hours) / miles = hours

With that knowledge, the equation for the problem you are given is:

(D mi / 525 mph) - (D mi / 600 mph) = 40 min

And you are being asked to solve for D(istance).

(I'm going to put 2/3 hours instead of 40 min now to make it simpler.)

The above is the same as:

(600 D mi / 525 x 600 mph) - (525 D mi / 525 x 600 mph) = 2/3 hr

Which equals:

75 D mi / (525 x 600) mph = 2/3 hr

75 D mi / 315000 mph = 2/3 hr

D mi / 4200 mph = 2/3 hr ---------Divide both sides by "hr", so to speak:

D mi / 4200 mi = 2/3

D mi = 2/3 (4200 mi)

D mi = 2800 mi

If x hrs is the time taken to fly y miles at 600 mph

600x = y

So time taken on the other journey x + 40

So 525 (x + 2/3) = y

So 525( x + 40) = 600 x

525x + 350 = 600x

75x = 350 so x = 4 2/3 hours x 600 mph = 2800

600x = y

the time taken for the return trip= x + 40

525 (x + 2/3) = y

525( x + 40) = 600 x

525x + 350 = 600x

75x = 350 so x = 4 2/3 hours x 600 mph = 2800

the answer is 2800 miles

hope this helps (xxxxxxxxxxxxxx)