Sumif - how to write the formula

Hello, I'm new to the forum. I'm not good with writing formulas, so I'm hoping to get some help.
I have a spreadsheet with columns A through O. I have conditional formatting in Column B that turns certain values to a specific color.
Example: If the Value in Column B is "Q1", it turns the whole row purple. I want to add up all of the values in Column M if the value in column B is "Q1". I'm thinking the SUMIF function can do this for me, but I don't know how to write the formula. The data range is A10:O149.
Will someone please help? Thanks!

-Connie

That's it! Thank you! By the way, I'm Greek and Cypriot American!

Regrettably only a few phrases. I can read but I have no idea what I'm reading! My parents didn't speak Greek around the house very much.
By the way, how do I mark this thread as "solved"?

efharisto poli! Ah! I don't have Greek font!