Answer: 3
Step-by-step explanation:
Let E be the event of that student pierces ear and N be the event of that student pierces nose.
Given: 

For any two event A and B, we have

Similarly , 

Hence, 3 students have piercings both on their ears and their noses.
The answer would be B. Using the foil method to check, the two k's equal k^2, then the k and -f would equal -fk, plus the 2fk would equal a positive fk. Lastly, the 2f and -f would equal -2f^2.
If 2 lines intersect to farm a right angle , they are perpendicular ....... I hope that help
2/3
Step-by-step explanation:
the anwser would be either 2/3 or 1/3