[ Yes, Reiji is very smart, and yes, Leon doesn't have anyone else who can stand his lack of... knowledge in general. So out of nothing but pity for this mere mortal that is Leon, Reiji will offer a helping hand. ]

Yes...yes. I guess it can't be helped, let's see...

[ He shifts slightly closer to Leon, but not too much because personal space, though Leon never seemed to learn the meaning of those words. He taps his finger on a formula written in their textbook. ]

You'll have to use this to find 'a'. You have the value of 'b', so...

[ Reiji explains it in a simple way, simple enough that even people like Leon and Daiya can understand. No, he wasn't going to let Leon look at his work directly this time. ]