Excel 2007 :: Sum In Table Based On Another Cell Value

I have been tasked with doing a work tracker so we can see what work operatives have done between a date range. The processing of the date range is being done in VBA.

The tracking info comes from an external table that is linked into Excel (version 2007). This table is also filtered.

The problem I have is that there are 3 different tasks that the operative can be doing (each has a different time on how long it should take to complete the task, however that is irrelevant for what I need).

This results in multiple entries in the table (min of 1, max of 3) for each operative. There is a seperate column in the table as well which has the total number of each task that they have done.

So for example the table looks similar to this.

Clock No - Task - Sum of task
239 ------- A -------- 5
239 ------- B ------- 10
239 ------- C ------- 15

What I want to be able to do is to get the sum total for the sum of tasks for the operative, so in the above example for operative 239 I want a value of 30

Is there a formula that can do this? (it is a filtered table so the formula needs to count only visible items)

I have tried playing around with

=SUMPRODUCT(SUBTOTAL(3,OFFSET($A:$A,ROW($A:$A)-MIN(ROW($A:$A)),,1)), --($A:$A=K414315))

but I cant get what I need.