*URGENT* I NEED HELP WITH THIS QUICK

The function:
f ( x ) = x * 0.965^t
where x is the initial amount and t is the number of the years
80 = x * 0.965^3
80 = x * 0.89632
x = 80 : 0.89632 ≈ 89

The initial amount of animals was 89.

Hope this helps!
Have a nice day :)