Need help with formula

[Guest]

Company has formula for fuel review, I will need to check this quarterly but have no idea how to work out , and can't ask .
New Adjusted Rate = Rate*(1+N/P/107.49) - 1* 17%
I know
Adjusted Rate = 16.46*(1 + 99.73/107.49) -1 * 17%
I need to be able to work out the adjusted rate, and the percentage change between new and old rates.
Thankyou