Question 1071323
speed of cargo plane=x
passenger plane's speed=x+100
time before same distance was 4 hours for cargo plane, 3 hours for passenger plane
cargo plane flew 4x miles; passenger plane 3(x+100) miles.  The two are equal.
4x=3x+300
x=300 mph for cargo plane, flew 300 miles before passenger plane left and another 900 miles before caught.
x+100=400 mph for passenger plane, which flew 1200 miles in 3 hours before catching cargo plane.