Question

Laura left Dunkin Donuts at 1 PM traveling 30 mph. Two hours later her friend Jen left the same Dunkin Donuts and started after her on the same route traveling 45 mph. At what time will Jen catch up to Laura?

Answer 1

It took Jen 4 hours to catch up with Laura

Explanation:

Gaining speed 45-30= 15 mph

Laura's head start 30×2=60 miles

Time for Jen to catch up 60÷15= 4 hours

In other words

30(t+2)= 45t

30t+60= 45t

60=45t-30t

60= 15t

t=4 hours