I was just trying to teach my Younger Brother (5th Grader) BASIC Programming.

Well it was going on well untill I wrote this to
Explain how we asign values to variables.

Initially
a = 1
b = 2

now if

a = a +b

then a = 3

Now my brother is arguing how

a = a + b can be possible if b is not equal to zero.

I tried to explain to him that it is just a way of writing in Programming languages.

He called me an Ediot (I deserve that ).
Is there any way I could explain to him and justify such a syntax ?