250 seconds because it takes Mary 50 seconds to get around the track (300feet/6ft/sec) and it takes Peter 300 seconds to get around the track (300ft/1ft/sec) so if you subtract the fastest time from the shortest time you get the amount of time that Mary had to wait for Peter to get there, so after 250 sec (300sec-50sec) Peter, Paul, and Mary are reunited.
H=2f/m+1 subtract one from both sides h-1=2f/m multiply m to both sides m*h-1=2f divide 2 both sides mh-1/2=F (the whole left side of the equation is divided by 2 i just cant do it on the computer)
