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Answer:
You should use photomath, it would be more easier for u. Oh, and by the watñy Y=12
15/7*7/2*4/5=15/2*4/5=60/10=6
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.