I need a basic formula that my brain is failing to give.

Hello again forum,

I'm trying to boost some sales on my products by repricing but my think box is failing me on this equation.
SO... spread.. I have a spread of my products, cost, price, and all the fun stuff.. I need my calculated GP (Gross Profit) to be down to 10%. Meaning, I have thousands of items here with all sorts of GP's from 10% to 100% I want no matter what the current GP is, I need the price to be brought down to make my GP only 10%. So the variable is where I'm getting caught up, I need to solve for X and I don't know how. So in words (if I can explain this correctly) Cost minus Price divided by cost will get my current GP. The equation I need will calculate my current GP or just pull it from the calculation I already have and solve for X(current GP) and bring that GP down with end result being: My 100$ item has a 100% GP.. by making that item 10$ I lower my GP to 10% which is goal.
I know I'm repetitive but it's hard for me to explain things. Any help on this would be greatly appreciated, THANK YOU!


-Tommy Bailey