Aboy faces north. he turns left until he faces east. how many right angles does he turn?

That is so easy, the answer is 1 right angle.North is to front and east is to the right so it is just 1 right angle.

This can be done 2 ways. Like this:- 

Way #1:-

North then turn West (thats 1 right angle) then turn south (2nd right angle) and last but not least turn east (3rd right angle). So if we do it this way the boy turns 3 right angles.

Way #2:-

Boy starts at north and turns to east. This has 1 right angle.