Answer:
$429
Explanation:
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![(312)/(800) =(x)/(100)](https://img.qammunity.org/2022/formulas/mathematics/college/4j3x1x4ag2r8tzsxpynxowrj24in7apry9.png)
Cross multiply
![800x=31200](https://img.qammunity.org/2022/formulas/mathematics/college/hv6tid0v168em06kq262s8gq3y009qa3gk.png)
Divide both sides by 800
![x=39](https://img.qammunity.org/2022/formulas/mathematics/college/3abzwq5yxz384opnxqfxgc08p2mdyxriw2.png)
So, Niu earned 39% on the investment of $800
So, let's find out how much $1,100 would have earned him in the same investment.
--------------->>>>
![(x)/(1100)=(39)/(100)](https://img.qammunity.org/2022/formulas/mathematics/college/fhtbgzax2ndopu7kw13zhpb8mnka6kjeqk.png)
Cross multiply
![100x=42900](https://img.qammunity.org/2022/formulas/mathematics/college/y4cadd7pluxod8qhi5kx5opogst9s3edkq.png)
Divide both sides by 100
![x=429](https://img.qammunity.org/2022/formulas/mathematics/college/pw8lvher5lltqlnxa5qsutfzh8u5b03dmx.png)
--------------------
This means that Niu $1,100 would have earned Niu $429 in the same investment.
Hope this is helpful