By sampling, it is estimated that there are 20 000 trout in a lake. Assume that the trout population, left untouched, would increase by 15% per annum. It is known that 2000 trout per year are removed by fishing.

a. How many trout are there in the lake after:
i. 1 year ii 2 years iii 3 years?

b Write a recurrence relation that gives the number of trout in the lake after n years in terms of the number of trout in the lake after n − 1 years.

c Write a formula for the number of trout in the lake after n years in terms of n.

d Find the number of trout in the lake after 15 years.

I understand up until c. Thank you for any help :)