for weak 1 if we implement w=1 we see that f(w) = 18
we can see that w represents number of weeks. Observing f(1) and f(2) and etc we can see that each next week number of laps is increasing by 10
f(2) - f(1) = 10
f(3) - f(2) = 10
that means that 10 represents number of laps jessica swims each week.
