Question

Two planes left Orlando International airport approximately the same time and fly in opposite direction .Their speeds are 510 miles per hour and 600 miles per hour How far apart will the two planes be after 90 minutes ????

Answer 1

600+510=1110

300+270=570

1110+570=1680

Answer 2

Distance = rate * time, the miles per hour, means you need to change the 90 minutes to hours, or convert mph to miles per minute.  90/60(510+600)=1665 miles.