Set a starting capital, how much is added or withdrawn, the month it happens, the other partner’s flat capital, and the profit. Step four always computes the average-capital route beside the true segment sum, so you can see when the two agree and when they do not.
₹5,000 dropping to ₹4,000 at month 4
13 : 18 · 13,000 and 18,000
Set the change to month 6 and the average matches the segment sum exactly, because each capital then ran for half the year. Move it to month 4 or 8 and the two part company.