AverageIF function for non-contiguous data

Hi all
I have data arranged in a row, grouped in pairs of columns, such that column A is the descriptor, B the value, C descriptor, D value etc.
I want to average all values in the in row where the descriptor matches a certain criterion - actually a certain number.
Therefore I would be averaging every second column on the same row IF the adjacent column met the criterion ie a certain number.
I cannot get the AVERAGEIF function to work, presumably because of the non-contiguous nature?
Does anyone know how to achieve this?

My attempt was this: =AVERAGEIF((P7,R7,T7,V7),"=100",(Q7,S7,U7,W7))

Thanks

You can use the AVERAGEIFS function:

=AVERAGEIFS(B2:H2,$A$1:$G$1,"Descriptor",A2:G2,"=100")

Thank you this is an excellent suggestion.
But it relies on the column header having the same heading ie "Descriptor"
I necessarily have to have each column header different.
Is there a way around this?

If it helps . . . each column header for the desciptor column will start with the same text ie Prod - I was trying to find a way to incorporate the LEFT(4) function in to your formula so that perhaps it could reference the first 4 letters of each descriptor column and therefore identify the "Prod" . . .

Change "Descriptor" to "Prod*"

=AVERAGEIFS(B2:H2,$A$1:$G$1,"Prod*",A2:G2,"=100")

You legend. Thank you.