a = 750, the number of fish in the year 2005.
8.3% = 0.083, the growth rate
Let n = the number of years, counted from 2005.
Let a(n) = the number of fish after n years.
When n=1, a(1) = 750*1.083
When n=2, a(2) = 750*1.083²
When n=3, a(3) = 750*1.083³
Therefore, after n years, a(n) = 750*1.083ⁿ
The number of years between 2005 and 2050 is 2050-2005 = 45
Therefore in the year 2050, the number of fish will be
a(45) = 750*1.083⁴⁵ = 27123.26
We cannot have fractional fish, so a(45) =27123.
Answer: 27123