Let x be the amount invested at 10% and y be the amount invested at 8%. We know that:
x + y = 18389 (equation 1)
0.10x - 0.08y = 621.02 (equation 2)
From equation 1, we can solve for y:
y = 18389 - x
Substituting this into equation 2, we get:
0.10x - 0.08(18389 - x) = 621.02
0.10x - 1471.12 + 0.08x = 621.02
0.18x = 2092.14
x = 11623
Substituting this back into equation 1, we get:
11623 + y = 18389
y = 6766
Therefore, $11623 is invested at 10% and $6766 is invested at 8%.