Reverse-Engineering a Pricing Formula

[danptak]

I'm trying to reverse engineer this formula for a client: http://advantagefutures.com/Introduc...mmissions.html

It's relatively straight forward: If you execute 90 trades, it's just $.99x90. If it's 1,000 trades, it would be 100 x $.99 and 900x $.69.

Any thoughts on how to structure the formulas for each level? Does excel require If/Then statements?

Thanks!
Dan

[shg]

The cost for n trades is =0.90 * n - 0.21 * (n>100) * (n-100)

[darknation144]

Did this work?