Out of 50 student in competition, 6 student taking foot ball, 12 students basket ball and 15 students taking vally ball, if 2 student taking basket ball and foot ball, 2 student taking basket ball and vally ball and 3 students vally ball and foot ball I how many students taking all games?

Answer 1

Your numbers do not add up.
Usually, when you say "6 student taking foot ball" it means those who take football and maybe also at least one of the other sports.

But you seem to be saying that 6+12+15 = 33 students play some sport or other. But if it's a competition, don't all 50 students play something?

So, OK, let's say that only 33 students participate in these three sports. But, applying the usual semantics, we get
33-(2+2+3)+x = 33
x = 7 play all three sports.
But, if only 2 play basketball and football, how can 7 play all three?

This question has been unforgivably garbled.

Remember: It's not my job to figure out what you mean.
It's your job to say it so clearly you cannot be misunderstood.