Can anyone me solve this saw it in a yt video for our class and cant seem to figure out where he got 1/6

∑u (-3) + (1 - ∑u) (1) = ∑u (2) + (1- ∑u) (0)

∑u is equal to the probability that player 1 goes with option 1 or "up" like he described in the video.

you can find the video on yt it is called : game theory 101 mooc (#8): the mixed strategy algorithm

i know its inverse operations