In a classroom, there is a jar filled with 50 pencils. The teacher, Mr. Smith, takes out 5 pencils for himself and leaves the room. While he's gone, student A takes 10 pencils without anyone noticing. Student B notices that there are fewer pencils than before and adds 15 more pencils to the jar. When Mr. Smith returns, what will each person think about the number of pencils in the jar? Provide a brief response.
When Mr. Smith left the room, there were 45 pencils in the jar after he took out 5. After student A took 10 pencils, there were 35 pencils left. Then, student B added 15 pencils, increasing the total to 50 pencils.

Mr. Smith will think that the number of pencils in the jar is the same as before since he is not aware of the changes that took place while he was gone. 

Student A will know there are 50 pencils in the jar because they were aware of taking 10 and will also see the result of student B adding 15 pencils, which restores the number to the original count.

Student B might think there are more pencils than originally because they saw a jar that had fewer pencils than before and added 15 to it, not knowing that only 45 pencils were there when they decided to add more. Therefore, without knowing the exact starting count when they added the 15 pencils, student B would likely be under the impression that there are now 65 pencils if they assumed the jar started with 50 when they first looked.