You travel 5 miles downstream in a kayak at a speed of r miles per hour. You turn around and travel 6 miles upstream at a speed of 0.75r miles per hour. Finally, you turn around and return to your original starting point at a speed of r+1 miles per hour a. Write a model in simplifies form for the total time t (in hours) of the trip.
b. How long does your trip take when r is 5 miles per hour?