A pilot flies to an airport at an average ground speed of 100 miles per hour. Because of an unfavorable headwind, he returns over a course 80 miles longer than the course he took on the previous trip. His average speed is 80 mph, and the trip takes 3 hours longer. What is the distance of each of the two courses he flies?

let x=distance of first trip.

then (x+80)=distance of return trip

time of travel=distance/speed

return trip took 3 hours longer

(x/100)+3=(x+80)/80

(x+300)/100=(x+80)/80

80x+24000=100x+8000

20x=16000

x=16000/20=800 miles

first trip distance = 800 miles

return trip distance =x+80=800+80= 880 miles