Ron Dorris is on his way to San Diego, 300 miles away. He drives 45 miles per hour for 3 hours. He drives 55 miles per hour for the rest of the trip. How long does Ron drive at 55 miles per hour?

Answer 1

3 hrs @ 45 mph = 135 mi

300 mi - 135 mi = 165 mi

165 mi @ 55 mph = 3 hr.

Answer 2

45*3 + 55x =300

55x= 165

x=3 hrs