Hi I need to do a function, I have the following columns and some sample data

Name Week Number. Estimated Hours
Yvonne 4 2
Yvonne 4 3
Simon 4 5
Yvonne 5 1

What i want to do is, for each person i want to some their total estimated
hours for week 4.
So in pseudocode im trying to do this:
SUM the estimated hours where the name = Yvonne and the week number = 4.
The answer should be 5 for this example

Can someone please help me to do this, im struggling.

Thanks.
Simon