Karin biked at 13 mph for a time but got a flat tire. She then walked at 5 mph. She traveled a total of 93 miles. Had she biked the whole time, she would have gone 117 miles. How many hours did she walk?
distance=rate*time
117=13*time solve for time.
Now,
93=13*timeride+5*(timeabove-timeride)
solve for time ride, then subtract it from the first time found.