A plane left at 3pm flying west at 450 miles per hour At 330

A plane left at 3pm flying west at 450 miles per hour. At 3:30 pm another plane left the same airport flying west at 500 miles per hour. At what time did the second plane overtake the first plane?

first plane speed 450 mph
second plane speed 500 mph
rt=d
RT=D
30 minutes head start=1/2 hour
450*(t+1/2)=500(t)divide by 50
9*(t+1/2)=10t
9t+4.5=10t
simplify
4.5 hours =t
They pass at 7:30 pm