Help with a formula

Hi guys,

I have a variety of products that i sell out to different agents at various levels of commissions. These range from a possible earning for the agents from 12%-30%.

Is there a set formula that will take my initial buying price ie £100 and i wish to earn £5 regardless of whether the agent earns 12% or 30%.

so an agent on 12% would buy from me at £119.32 and an agent on 30% would buy from me at £150

any ideas

cheers
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