Happy new year! Guys, maybe you could help me with the following.

For school I'm looking for a formula to be able to avoid a circular reference. Let me explain further:
I want to determine a sales price in a formula, with a variable which is called 'profit' in %. I have a certain amount of costs and over that there should be a profit % and that will result in a sales price. All cool so far, but in the total amount of the costs is a commission which is determined as a % of the salesprice, that's where the circular reference comes from. I heard some things about a goal seek but I'm not sure if this works for me, does anyone have any ideas?

Thanks in advance!

Best regards,
Christian Hoedeman