calculate average but don't include the value

[IHam]

I am trying to calculate a mean for an examination sitting but finding the average of values not including the value itself in dax. 

Any help would be great.

To illustrate:

subject	sitting	mark	"average"
maths	summer 2023	60	(70+80+90+50)/4
french	summer 2023	70	(60+80+90+50)/4
english	summer 2023	80	(60+70+90+50)/4
biology	summer 2023	90	(60+70+80+50)/4
history	summer 2023	50	(60+70+80+90)/4

[IHam]

Many thanks to both of you - they both work but the second solution is the one that seems to match my set-up.

[ThxAlot]

[Dangar332 · Accepted solution]

HI, @IHam 

Measure 2 = 
var a = CALCULATE(SUM(sub[mark]),sub[subject]<>MAX(sub[subject]))
var b =CALCULATE(DISTINCTCOUNT(sub[subject]),sub[subject]<>MAX(sub[subject]))
return 
DIVIDE(a,b)