v = speed of fastest swimming = 8.6 kilometer/hour
V = fastest speed of a tennis ball = ?
It is given in the question that
fastest speed of a tennis ball = (13.07) speed of fastest swimming
V = (13.07) v
inserting the values
V = (13.07) (8.6 kilometer/hour)
V = (13.07 x (8.6) kilometer/hour)
V = 112.4 kilometer/hour