HELP PLZ :) A lake is rising at a rate of 4 inches per hour. If the lake rises more than 36 inches, then it will cause flood damage. How long can the lake rise at this rate without causing flood damage?

Cody started biking to the park traveling 15 mph, after some time the bike got a flat so cody walked the rest of the way, traveling 4 mph. if the total trip to the park took 6 hours and it was 46 miles away, how long did cody travel at each speed? solve using rate times time= distance