Let x be the amount loaned at 5% annual interest, then the amount loaned at 4% annual interest is $36,000 - x.
The interest earned on the loan at 5% annual interest is 0.05x, and the interest earned on the loan at 4% annual interest is 0.04($36,000 - x) = $1440 - 0.04x.
The total interest earned on both loans is $1625, so we can set up the equation:
0.05x + (1440 - 0.04x) = 1625
Simplifying and solving for x, we get:
0.01x + 1440 = 1625
0.01x = 185
x = 18500
Therefore, $18,500 was loaned at 5% annual interest, and $17,500 ($36,000 - $18,500) was loaned at 4% annual interest.