Population.When the population of a certain species was found to be at a critically endangered level in 2021, conservationists recommended some ways of saving the species. If the recommendations are followed, the rate of change of the population of the speciestyears after 2015 is expected to be represented by

P(t) =

-285/3t		if 0t6
138(t-3)^2 +240		if 6 <t11

Note: Enter your answer as a whole number or integer. (a) The rate of change of the population in 2021 (t= 6) is (b) The rate of change of the population expected to be in 2025 is