I am trying to set up a formula each time the data changes in column A
without having to do it manually.

The formula would be using two other columns of data for the rows involved
with the same company.


e.g.

Column A Column Y

2 Company ABC

3 Company ABC

4 Company ABC =SUM(W2:W4)/SUM(R2:R4)

5 Company def

6 Company def

7 Company def

8 Company def =SUM(W5:W8)/SUM(R5:R8)

9 Company xyz

10Company xyz =SUM(W9:W10)/SUM(R9:R10)