If the population is declining by 13% every year, this means that at the end of the year the population is 87% of the population at the start of the year.
This is an exponential behavior expressed as:

Where P(t) is the population of foxes after t years, A is the initial population, and b is the percentage (87% in this case). From the problem, we identify:

The final model is:

After 8 years (t = 8), the population will be (to the nearest whole number):
