1st /5th /Cheryl
2nd /4th /Laura
3rd /3rd /Sally <
4th /2nd /Anne
5th /1st /Betty

Seems like the answer has to be 99. There are no ties, and Sally is 3rd best and 3rd worst out of five. There are not 6 people in the group, but five because a number has to be odd to have a middle integer. 3 is Sally's rank. 3x21=5. So, for Peter Pans's question: 50 is Sally's rank. 50x21=99
The answer then, is 99.
EDIT: When I subtract 1, I am subtracting Sally.