A mathematics teacher came into the class and asked the class to find x in the following equation 2+5-7=x find x,when he turn to face the class he saw the whole class bending and searching for something except one student,so he asked the class what are you all searching for,class replied:but sir you asked us to find x so that is actually what we are looking for...then the student that wasn't searching quickly said:you all are very foolish I swept this class this morning so I didn't see any x