I am trying to return the address in an array for a value within that array.

Example

A B
1 5/10 7
2 5/11 10
3 5/12 12
4 5/13 9
5 5/14 15

I would like to return the address A3 when I look up the date 5/12 in the
array. Ultimately, I would like to manipulate the data in column B
corresponding to the row returned from looking up 5/12. For instance, I
would like to sum the numbers from B3 to B5. Or if I look up 5/11 to sum the
numbers from B2 to B4.

Help!!!