Row & Large Function

[Moe]

What I'm trying to do is this: I have a list of numbers in A1:A100, I need to find the largest number in A15:A30 and subtract from it the number in the cell immediately above it. Ex:

10
15
17
2
20
5

I would want my formula to give a result of 18. (20 - 2).
I started with large(A15:30,1) but not sure how to capture the row that 20 falls in?

Thanks,
Moe

[Ron Coderre]

This is one way to do it:

=LARGE(A1:A5,1)-INDEX(A1:A5,MATCH(LARGE(A1:A5,1),A1:A5,0)-1)

Regards,
Ron