Answer:
3
My logic:
so she jars 10 on the first day (that is 1 day) and she wants to jar 16. so if you subtract 10 from 16 you get 6. Now we know she wants to jar 6 more, and if she does 3 every day then you would divide 6 by 3 and get 2. 2+1 is 3, so 3 days. (if you cant chose 3 chose 2 because your teacher might not want yo to count the first day)
Hope this helped!