Answer:
$429
Explanation:
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Cross multiply

Divide both sides by 800

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.
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Cross multiply

Divide both sides by 100

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This means that Niu $1,100 would have earned Niu $429 in the same investment.
Hope this is helpful