please help meee!!!

Question

The area, A, of a forest, in acres, is modeled by the equation A = 5000 (5/4)d where d is the number of decades since the beginning of the year 1950.

What is the area of the forest in 1940?

Answer 1

1. The area of the forest increases with time because the growth factor 45​ > 1.
2. The area of the forest in 1950 will be A=5000 acres. We get this by plugging in d = 0 in the given equation A=5000⋅(5/4​)^d = 5000 acres.
3. To calculate the area of the forest in 1940 now. notice that when we do so we have to plug in d = -1 since we are calculating the area 10 years before. d is in decades, a decade is 10 years So plugging in d = -1 (because we are calculating before) in the equation we get  A=5000⋅(5/4​)^−1 =  5000⋅(4/5)^1 (we are using the law of exponents here) = 4000 acres.
4. No, the area of the forest is not less than 1,000 acres in 1990 this is because 5000⋅(4/5​)^−5 = 1638.4.This is > 1000.