From the given information, we know that the sum of the interest must be equal to the total annual interest of $15,000. So, we can write
[tex]0.10x+0.08(175000-x)=15,900[/tex]
where x denotes the amount of money at 10% and (175000 -x) the amount of money at 8%. Then, our last equation is equivalent to
[tex]0.10x-0.08x+14000=15,900[/tex]
Then, by subtracting 14000 to both sides, we have
[tex]0.10x-0.08x=1,900[/tex]
and by collecting the terms on the left hand sides, we have
[tex]0.02x=1,900[/tex]
Now, by dividing both sides by 0.02, we obtain
[tex]\begin{gathered} x=\frac{1,900}{0.02} \\ x=95,000 \end{gathered}[/tex]
Then, $95,000 is the amount paid off at 10%.
Now, by substituting this result into (175000 -x), which corresponds to the amount paid off at 8%, we get
[tex]175,000-95,000=80,000[/tex]
Therefore, the answer is: $95,000 amount paid off at 10% and $80,000 amount paid off at 8%