I have the following example

1) Jim | Customer A | 2014 Sales | 375|
2) Jim | Customer B | 2013 Sales | 125|
3) Jim | Customer A | 2014 Sales | 500|

so, I basically have sales info, some having been entered multiple but unique times for a years reporting. I want to clean up my worksheet, to in the above example, make it look like:

1) Jim | Customer A | 2014 Sales | 875|
2) Jim | Customer B | 2013 Sales | 125|

I have a lot of these on my project, so the simpler to replicate the better. Running Excel 2013. Thanks!