I am hoping someone can help me out with this, as I seem to be brain dead at the moment :)

I have an amount that represents the sales tax we have collected for the last quarter. I need to be able to calculate what the total sales are from this number. The tax is 6%. I know what my total sales are, but some sales are tax exempt. I know there is a really easy way to calculate backwards to find the total sales that were taxed at 6%, but it seems to escape me at the moment.

I would appreciate it if someone can help :)

Thanks