Well sure, but even if 150 chinese yuan were equal to 11 USD, turning 20 yuan into 150 yuan wouldn't be like turning $3.25 into $11, it would be like turning $3.25 into $24.375. It might be metaphysically more like turning $1.47 into $11, but absolute quantities aren't really at issue when you're talking about return rates (I'm assuming the cockroach farm, which by implication earns in the tens of thousands of USD per year, can scale up beyond a return of 150 yuan). It would have been easier and less of a gaffe for the reporter to say "you can invest 20 yuan and get back 150 yuan, or $20 for a return of $150". Why did they bother to print a conversion at all?
There is some logic in the conversion as it helps show scale - if you run a lemonade stand it may be true to say you can invest $10 and profit $20, but not true that you could invest $1m and profit $2m, whereas in a car manufacturing business you might be able to invest $Xm and profit $2Xm, but investing $10 is unlikely to give you any return. These two scenarios can't both be explained as "you can invest 1 and get 2 back".
That said, a single quote, even with conversion, doesn't help much here - if a reader wanted to start a farm now it doesn't give them any idea of whether 20 yuan is the minimum or the maximum investment (I presume it's below the minimum anyway).