Answer:
Nico invest $2500 at 9% interest rate and $800 at 4% interest rate.
Step-by-step 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.
![x* (9)/(100)+(x-1700)* (4)/(100)=257](https://img.qammunity.org/2020/formulas/business/high-school/z7ixi73sl9zsazig117grjmve7kouufuyh.png)
![0.09x+(x-1700)0.04=257](https://img.qammunity.org/2020/formulas/business/high-school/5m1cl3zua1m0ejb690gs2rex3ja8u1ps69.png)
![0.09x+0.04x-68=257](https://img.qammunity.org/2020/formulas/business/high-school/grmz7ndpl8znlyrldiyoaentcz9rgtltoh.png)
![0.13x-68=257](https://img.qammunity.org/2020/formulas/business/high-school/1t4hp4b8kvjpfzqqsqaq8y985swwgxtxd6.png)
Add 68 on both sides.
![0.13x=257+68](https://img.qammunity.org/2020/formulas/business/high-school/s049niiyb0wh2spdp420xp9g9xhl9wtnaw.png)
![0.13x=325](https://img.qammunity.org/2020/formulas/business/high-school/s783adn2pj1dd6tqtz08fu7df8kh5aligw.png)
Divide both sides by 0.13.
![x=2500](https://img.qammunity.org/2020/formulas/business/high-school/ftmas395pg9vvzmeo9noy0wqq3s8r73fgd.png)
Nico invest $2500 at 9% interest rate.
![x-1700=2500-1700=800](https://img.qammunity.org/2020/formulas/business/high-school/alfvtlfdag80xnj51hb9eixdxpv52m7a9u.png)
Nico invest $800 at 4% interest rate.
Therefore Nico invest $2500 at 9% interest rate and $800 at 4% interest rate.