Obtaining the sum of certain values in a column based on conditions from 2 other columns

Hi team,

The attached spreadsheet shows data for YTD outages. Column A is the Time To Resolve for each outage (in hours). Column B is the month in which the outage occured (1 is Jan, 2 is Feb, etc) and column C indicates whether the outage was GCR-related or not (YES/NO).

NOTE: TTR equals downtime. It's the amount of time a certain application was down.

I have been asked to display what percentage of total downtime in each month were GCR-related. I'd like to be able to sum up the TTR's in January that also had a "YES" in the GCR-related column, then do the same for Feb, Mar and Apr.

I know how to do it manually, but can't I use some variation of SUMIFS to get the results automatically? I'm still learning the intricacies of these commands and I haven't been able to figure it out on my own...

Please see attached.

Thanks for your help!

p145