I feel like this is so simple but I just can't seem to pull it out of the aging brain......

I have aProduct Costrepresented asA

I have aFeefor the product that is a percentage of the Product Cost asBB=(A*.10)

This gives me theTotal Cost of the product asC

Now if I know the Product Cost is 500.00A=500

If the Fee is 10% of the Product Cost then 500*.10=50B=50(the Percentage is not always constant and can change but it is always based on the product cost of A)

A+B=C

500+50=550C=550

However, if I don't know the Product Cost but am only given the Total Cost and the Fee, How can I find out what the Product Cost is?

C=A+B

or

C=A+(A*.10)

How do I solve for A?

Thanks in advance