Subtotal question

I have no problem with the columns A and B after applying Subtotal, how do i get column C?

Raw data
# boxes
Store 1 2 John
Store 1 2 John
Store 1 2 John
Store 2 1 Paul
Store 2 3 Paul
Store 2 5 Paul
Store 2 2 Paul
Store 3 5 George
Store 3 2 George
Store 3 2 George
Store 3 1 George
Store 3 1 George


Result Desired [or similar using Subtotals]
#boxes
Store 1 6 John
Store 2 11 Paul
Store 3 11 George

You can use this formula in C19:

=VLOOKUP(A19,A$3:C$14,3,0)

then copy into C20:C21.

Hope this helps.

Pete