Any pros here

Hi,
I am working with a sheet.
There i have cell "price", margin % and price net.
I wanted to know if it possible to do like this that when i enter a number (%) in cell "margin %" then it will multiply with cell "price" and give the value in cell "Price net". this part is ok. But i wanted to do it vice versa. like this. exampel. The price for a product is 100 $ for me to get and i want to sell it with profit. So i might give excel how much margin in % i want then it will calculate and show price net or i may manualy enter the price i want it to be sold out for and the excel will show how much margin i will get from this price. Only with three cell. That i now is when i type a number in the cell where the formula is then the formula will be erased.

I hope u understod what iam trying to explain
Plz help!

Price :
Margin % :
Price net :