Answer:
Nico invest $2500 at 9% interest rate and $800 at 4% interest rate.
Explanation:
He invests some money at 9%, and $1700 less than that amount at 4 %.
Let Nico invest $x at 9%.
It means he invest $( x-1700) at 4%.
The investments produced a total of $257 interest in 1 yr.
Add 68 on both sides.
Divide both sides by 0.13.
Nico invest $2500 at 9% interest rate.
Nico invest $800 at 4% interest rate.
Therefore Nico invest $2500 at 9% interest rate and $800 at 4% interest rate.