Sales from advertisement

Did some1 see Amazon advertisement ad on seller page. “Other seller getting sales of 57$ for 1$ spent…”
I just used 20 Pounds of free advertisement and no sales…
I just want to ask if you guys do advertisement and how much you get sales for 1pound .

Thanks

Its depend on product demand and competition. There are many Factors
It could also be that your listing is not optimized and may be you have Low Reviews as compare to other sellers