Calculate when 1 column has different data

[HF85]

Here is what I’m trying to do.

If the data in column A and B matches the same data in Column A and B on another row, but the info in column C is different, I want to calculate the percentage between the two rows with data (numbers) in column AE.

Example:
A | B | C
State | County | 2
State | County | 4

Thanks!

 

[etaf]

not enough examples or expected results
% would that be 2/(2+4) so what is the first row as a % of the total - or the difference between the two - (4-2)/(4+2) or - (2-4)/(4+2)
something like
where i have used the 2/(2+4) example
=IFERROR(IF(AND(A1=A2,B1=B2),C1/(C1+C2),""),"")

will there only be 2 rows that match - and always one after the other

Book10
	A	B	C	D	E
1
2	State	County	2
3	State	County	4		33%
4	State1	County1
5	State2	County2	12
6	State2	County2	14		46%
7	State4	County4
8	State5	County5
Sheet1

Cell Formulas
Range	Formula
E2:E8	E2	=IFERROR(IF(AND(A1=A2,B1=B2),C1/(C1+C2),""),"")