This is a form of equation.
The first answer is given.
But what should replace the questionmark?
One attempt allowed.
Level: very hard.

Date 2017-01-23

Submissions            Correct            Not Correct

26                              2                    24

Solved by Tomas Perna,  CZ

Jason Betts,  AU

A first preliminary norm for this test after 15 submissions

Correct answered question     IQ +170 sd 15   can be expected