Average based on Value from a different Cell but in multiple columns

Hi Guys,
I need some help. I'm trying to figure out to combine multiple formulas in one.
I have a sheet where I look in column b for a value and want to calculate the average of the % in column D. So good so far but now I want to add the same thing for when I look in column F and calculate the average % in column H and so on. It would be nice if I could create that in one formula. Right now I'm doing

=AVERAGEIF(B:B,"M",D:D) then another one =AVERAGEIF(F:F,"M",H:H) and another one =AVERAGEIF(J:J,"M",L:L) and then =AVERAGE(P2,R2,T2)

Attached please find my sample file.
Every help is appreciated.
Thanks already,
Martin