In a class of $10$ girls and $20$ boys,Jaya's rank is $4$ among the girls and $18$ in the class. What is Jaya's rank among the boys in the class?

In a row of girls, if Savitha who is tenth from the left and Anita who is ninth from the right interchange their places, Savitha becomes fifteenth from the left. How many girls are there in the row?

In the following series of numbers,how many times have the figures $9, 1,$ and $8$ appeared together,with $1$ being in the middle and $9$ and $8$ being on either side of $1$ (i.e.,the sequence $9, 1, 8$ or $8, 1, 9$)?
$2, 1, 9, 8, 1, 9, 8, 3, 7, 1, 9, 7, 8, 1, 2, 9, 1, 9, 8, 1, 8, 2, 1, 2$

How many numbers between $9$ and $54$ (inclusive) are exactly divisible by $9$ but not by $3$?

Sangeeta remembers that her father's birthday was certainly after $8^{th}$ but before $13^{th}$ of December. Her sister Natasha remembers that their father's birthday was definitely after $9^{th}$ but before $14^{th}$ of December. On which date of December was their father's birthday?

In the sequence $5, 1, 4, 7, 3, 9, 8, 5, 7, 2, 6, 3, 1, 5, 8, 6, 3, 8, 5, 2, 2, 4, 3, 4, 9, 6$,how many odd numbers are there which are immediately preceded and also immediately followed by an even number?