On August 3 distance will be 5km + .1 + .1 + .1 = 5.3km
yes it is an arithmetic sequence because it increases at a constant rate ......each term differs from the previous term by a constant amount.
distance for nth term = (5 + .1n) km
If he starts at 5km on Aug 1st and THEN increases 0.1 km daily
distance for nth day = 5 + .1(n-1) on the n=16th day distance = 5.15 km