A plane climbs into the jet stream which is flowing at a rat

A plane climbs into the jet stream which is flowing at a rate of 80 miles per hour. It travels with the jet stream for 5 hours and then reduces its altitude, flying out of the jet stream for 4 more hours. The plane, while out of the jet stream, covered 550 miles less than it did during the 5 hours it was in the jet stream. How fast was the plane flying out of the jet stream?

Solution

In the jet stream the plane went
5*(j+80)
out of the stream it went 4j

5*(j+80)-550=4j
5j+400-550=4j
j=150 mph out of jet stream.
check
5*230-550=600
1150-550=600
600=600