I'm not all that familiar with that sort of representation, but I guess 3 3/4 = 15/4 and 2 1/6 = 13/6.
You will simply have to multiply the time spent walking, 13/6 hours, by the average distance traveled on an hourly basis, 15/4 km/h.
(13*15)/(4*6) = 195/24 = 8,125 km
I think the answer is B) The mean of the 5th and 6th values
