The sum of..

A little boy was doing his maths homework and was saying: 2+5, the son of a bitch is 7. 3+6, the son of a bitch is 9"

His mother asked: What are you doing?

Boy: I'm doing maths homework

Mom: Is this how your teacher taught you?

Boy: Yes

Infuriated, the mother talked to the teacher next day-"What are you teaching my son in maths?"

Teacher: Right now, we are learning addition.

Mom: "You teach then to say 2+ 2, the Son of a bitch is 4?"

Teacher said after laughing: "What I taught them was, 2+2, the some of which is 4"