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

In a queue,Vijay is $14^{th}$ from the front and Jack is $17^{th}$ from the end,while Mary is in between Vijay and Jack. If Vijay is ahead of Jack and there are $48$ persons in the queue,how many persons are there between Vijay and Mary?

In the Olympic Games,the flags of six nations were flown on the masts in the following way: The flag of America was to the left of the Indian tricolour and to the right of the flag of France. The flag of Australia was on the right of the Indian flag but was to the left of the flag of Japan,which was to the left of the flag of China. Find the two flags which are in the centre.

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 $2$?

How many even numbers are there in the following sequence of numbers which are immediately followed by an odd number as well as immediately preceded by an even number?
$8, 6, 7, 6, 8, 9, 3, 2, 7, 5, 3, 4, 2, 2, 3, 5, 5, 2, 2, 8, 1, 1, 9$

Nitin was counting down from $32$. Sumit was counting upwards starting from $1$ and he was calling out only the odd numbers. What common number will they call out at the same time if they were calling out at the same speed?