Question 273575
Two trains leave the station at the same time one heading due east at 85 mi/hr, the other heading due west at 65 mi/hr. After how long will the trains be 600 miles apart?

The trains are travelling in opposite directions

So the effective speed will be 85+65 = 150 mph

150 miles  --------1 hour
600 miles ---------? hours

600*1/150 = 4 hours

They will be 600 miles apart after 4 hours