Hi Barry,
Thanks for responding!
I guess we will have to leave it to the OP to try the formulas and do some manual calculations to see which gives the right answer. He should beware that our formulas are tested for how we each interpret his original question.
I interpreted that each 1/11th of a mile over whole miles is charged at 20 cents each and so if I enter $5.80 in my formula, it returns 2.0909 miles.
I used this formula to go from miles to $ :=1.6+TRUNC(F10)*2.2+MOD(F10,1)*11/10*0.2-(11/10*0.2), where F10 contains the # of miles and assumed the 1st mile is 1.60, each additional whole mile is $2.20 and each fraction of a mile after that is charged at $0.20/11th of a mile. So if I enter 2 miles, I get $5.78.
Then my attempt at reversing the formula so that you enter $ and get miles is what I posted: =TRUNC((G10-1.6+11/10*0.2)/2.2)+MOD((G10-1.6+11/10*0.2)/2.2,1)*10, which I admit is a little clumsy, but returns the correct reverse amount (i.e If I enter $5.78, I get 2 miles.)
As I said, the original poster has to decide on what his requirements are and what results he wants.