jack headed north

Question

Jack headed north from town at eleven oclock am at 20 miles per hour.  Jill left town 2 hours later traveling south. If they were 500 miles apart at 6pm, how fast was Jill traveling?

Answer 1

Jack traveled 7 hrs at 20 mph, i.e. 140 miles.

Jill only traveled for 5 hrs and went the difference between 500 and 140, i.e. 360 miles

That is Jill traveled 360 miles in 5 hrs, i.e. 360/5 = 72 mph