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.
X and 1 are common factors eh
Answer:
C
Step-by-step explanation:
14x4=56 and 26x2=52 so with process of elimination you get C
Answer:
12km/h
Step-by-step explana:
Let's call the total distance 2a from which we can calculate t1 equivalent to the first half of the distance a/10 similar to t2 is a/15 from which the total time is a/6 . We have the average speed equal to the total distance dduowcngf divided by the total inferred time by 2a/(a/6) which equals 12km/h
