** DISCLAMIER** am not completely sure. Please do not use my answer unless you are very desperate.
since O,R correspond with A,N I think you half F on each side and add it to 11.2 so 10 divided by 2 = 5 7 is already half. 5 + 7 is 12 12 + 11.2 = 23.2
IF THIS IS WRONG TRY 17 reason for 17: 10 + 7 = 17 If you look at both lines they look the same length as A, N.
