Calculate Sales price with Net Margin 10% Goal, if Cost goes up or down

I really need help,

I am having trouble figuring it out how to add the formula for sales price column to calculate price get Net margin 10% if cost goes up or down want sales prices to calculate as price 10% net margin

in Net Margin column formula I have

Sales Price -(Cost+Comm)/ Sales = Net Margin

up to now I add sales price manually, now I would to add formula to calculate sales price from net margin

my brain is not working , can some please help me with this, I am sure it must be really easy,

I have to add this to the file today, I really appreciate all the help in this matter.

hope my question is not confusing, please let me know if its does not make sense,

I just want Net margin to stay 10% no matter what the cost is and calculate the sales price from 10% net margin.

thanks in advance