My apologies if this question has been asked before.

I have a list of vendors and amounts paid for each of their invoices.
I want to automatically add the payments to each vendor.

TOTAL
VENDOR INVOICE PAID PAID
A 100 4526
A 250 4625
A 578 4626 928
B 10 SC17
B 186 SC350 196
C 541 Inv 56
C 325 Inv 78
C 18 Inv 102 884

What formula would do that without having to go and write a standard
Sum formula after every change of vendor?

Many thanks