Learning by Pattern Recognition

If you study the following figures,

+ 3 6 [first line]
9 [second line]

and

+ 2 4 [first line]
6 [second line]

and if I show you this figure,

+ 5 3 [first line]
_____ [second line]

what do you think should be written in the second line?

if your answer is 8 then congratulations. You have just learn a little of LISP Programming Language. Your brain discovered the answer though pattern recognition.