How would i go about solving the following problem?

Example Table:

A1: 10
A2: 15
A3: 20
A4: 5
A5: 39

How can i ask the computer to look through the values and find a group of
cells that sum up to a ceratin value so for example using the number 50 it
would identify that A1,A2,A3 and A4 add up to 50.

How would i go about doing that, this is to solve and try figure out what
invoices the customer paid when they send a cheque.

Thanks.