In a class of $20$ students, Alisha's rank is $15^{th}$ from the top. Manav is $4$ ranks above Alisha. What is Manav's rank from the bottom (in $^{th}$)?

Count each $7$ which is not immediately preceded by $5$ but is immediately followed by either $2$ or $3.$ How many such $7's$ are there?
$5, 7, 2, 6, 5, 7, 3, 8, 3, 7, 3, 2, 5, 7, 2, 7, 3, 4, 8, 2, 6, 7, 8$

How many $7$s are there in the following series which are immediately preceded by $6$ but not immediately followed by $4$?
$7, 4, 2, 7, 8, 4, 3, 6, 7, 5, 3, 5, 7, 8, 4, 3, 7, 6, 7, 2, 4, 0, 6, 7, 4, 3$

In a row of $16$ boys,when Pramod was shifted by two places towards the left,he became $7^{th}$ from the left end. What was his earlier position from the right end of the row (in $^{th}$)?

Madhu is $18^{th}$ from the left end and Sandhu is $11^{th}$ from the right end of a row of $40$ children. How many children are there between Madhu and Sandhu in the row?

In the series,$6, 4, 1, 2, 2, 8, 7, 4, 2, 1, 6, 3, 8, 6, 2, 1, 7, 1, 4, 1, 3, 2, 8, 6$,how many pairs of alternate numbers have a difference of $2$?