an airplane and a jet aircraft cross each other at different

an airplane and a jet aircraft cross each other at different altitudes traveling in opposite directions the jet travels 5 times the rate of the airplane. In 3 hours they are 1620 miles apart. find the speed of each aircraft.

Solution

3(5x+x)=1620
15x+3x=1620
18x=1620
x=90 mph
5x=450 mph