How many words can be made from the letters of the word $DELHI$,if $L$ comes in the middle in every word?

The number of straight lines that can be formed by joining $20$ points,no three of which are in the same straight line,except $4$ of them which are in the same line.

The total number of $3$-digit numbers,whose sum of digits is $10$,is

$4$ buses run between Bhopal and Gwalior. If a man goes from Gwalior to Bhopal by a bus and comes back to Gwalior by a different bus,then the total number of possible ways is:

The number of ways in which $6$ distinct rings can be worn on the $4$ fingers of one hand is:

How many $5$-digit even numbers can be formed using the digits $1, 2, 5, 5, 4$?