Not sure if this is a question..
It can be shown as a sign of respect. Most cultures use respect, honor and dignity to display ur social class, and ur way of life.
wa nani no hidesu ka thats you're answer
Yes he should have to apologize because he is interrupting the classroom coming in late.
Answer:
You may divide by a variable. But only if you know the variable is non-zero. So, if setting the variable to zero makes both sides of the equation zero, we have a solution that that variable is 0, or the equation with the variable divided out holds. E.g. solve x(x-1) = 0.
so yea have a grate day