Hello, Can someone help me. I work for a charity and we make cakes, my boss told me that I have to work out how much to sell the cakes at. He wants the retail price to be the cost plus 70%

An example is is cost me 30 pence (£0.30) to make my brownies and he wants me to add 70 pence (£0.70) so he wants to sell them at £1.00

is there an equasion I can use to calculate the retail (sale) price for all my other cakes as they all cost different prices to make.

I have been multiplying the cost to make it by 3.3334 but he said this was wrong.

I know I should know this but its been a very long time since I have been at school. So I hope that someone out there can explain it to an old girl.

Many thanks Emma