To begin with, note that the equation is for a 3 year debt, which is what is requested in the question. This means that we can use the equation.
Now, the $10,000 is just additional information meant to make you confused. Whether it is there or not does not make a change, unless there are other parts to this question which you did not state here.
Therefore, all we need to do is to substitute in what we are given:
r = 18.4
When r = 18.4, we will get:
l / 175.393 + 0.663 = 18.4
l / 175.393 = 17.737l
= 175.393 x 17.737l = 3,110.94564, which we can round off to $3,110.95