Simplifying a SUMIF over multiple columns

Hello,
I am thinking there is a simpler way to write a sumif formula for a criteria occurring in multiple columns. Please see attached (at least, I believe it is attached).

I am trying to total vendor amounts, but the same vendor can be listed in different columns, with an associated dollar amount in respective adjacent columns, as per the attached. I have a formula that works, but it is clumsy:
=SUMIF(B$7:B$319,AB7,C$7:C$319)+SUMIF(D$7:D$319,AB7,E$7:E$319)+SUMIF(F$7:F$319,AB7,G$7:G$319)+SUMIF(H$7:H$319,AB7,I$7:I$319)+SUMIF(J$7:J$319,AB7,K$7:K$319)+SUMIF(L$7:L$319,AB7,M$7:M319)



Tips on simplifying? Any help is appreciated.
Thanks in advance, and apologies if this has been posted before.

Thank you for your responses. I tried Tony's solution and it worked, so I rolled with that. I did tinker around with Jacc's, but need to trouble shoot, as i wasn't totaling up correctly....my error, I'm sure.

Thanks again.