How many $7$'s are there in the following series which are preceded by $6$ but not preceded by $8$ (i.e.,the sequence $6, 7$ where $6$ is not immediately preceded by $8$)?
Series: $8, 7, 6, 7, 8, 6, 7, 5, 6, 7, 9, 7, 6, 1, 6, 7, 7, 6, 8, 8, 6, 9, 7, 6, 8, 7$

In the sequence $7, 8, 9, 7, 6, 5, 3, 4, 2, 8, 9, 7, 2, 4, 5, 9, 2, 9, 7, 6, 4, 7$,how many $7$'s are preceded by $9$ and followed by $6$?

In a row of $35$ children,$M$ is $15^{th}$ from the right end and there are $10$ children between $M$ and $R.$ What is $R$'s position from the left end of the row?

In a row of girls,Rita and Monika occupy the ninth place from the right end and tenth place from the left end,respectively. If they interchange their places,Rita and Monika occupy seventeenth place from the right and eighteenth place from the left,respectively. How many girls are there in the row?

How many $8$'s are there in the following number series which are exactly divisible by their immediately preceding and also divisible by their immediately succeeding numbers?
$8, 2, 4, 5, 1, 7, 2, 8, 4, 8, 4, 2, 2, 8, 2, 6, 9, 8, 4, 5, 4, 8, 3, 2, 8, 4, 3, 1, 8, 3$

Hemang is $16^{th}$ from the top and $12^{th}$ from the bottom in merit in the class. How many students are there in the class?