Solution:

The letter 'X'.

X - 24th Letter of the alphabet.
XX - 20 in roman numerals.
XXX - labels for movies that are not clean.

Solution:

Kid1, he was left with one rock.

Solution:

The girl was born on 29 February. Thus her birthday came once in four years only while her sister was born on a normal day and celebrated her birthday every year. Thus the girl had a chance of depositing money only 10 times in 4 years through which she collected $2500 while her sister took $50 from the piggy bank every year making the total amount to be $2000. Thus when the piggy bank was opened, it had just $500.

Solution:

The husband had booked two tickets for departure and only one for the return. The travel agent told this information to the police and they immediately came to know that he had planned the murder right from the beginning.

Solution:

Treasure Map Is Hidden Inside The Hanging Room Floor.

Explanation.
Just reverse the text "roolF mooR gnignaH ehT edisnI neddiH sI paM erusaerT".

Solution:

It can be down as shown below.

Solution:

He askes the god to beat him half to death.

Solution:

-3 -1 1

Explanation:
-3 * 1 * -1 = 3(prime)
-1 - (-3) = 1 -(-1) = 2

Solution:

888 + 88 + 8 + 8 + 8 = 1000

Solution:

41312432

Solution:

2100 miles.

Each vowel equivalent to 500 and each consonant equivalent to -200