What has many keys but can’t open a single lock?

ENEMY = 2 * LINK
LINK + 2 = HELL

Then what will be TAXI + HELL? Select from the options below:
a) ROTTEN
b) DANGER
c) HEAVEN
4) MORTAL

If EELS + MARK + BEST + WARY = EASY

What does HELP + BARK + WARD + LEAD equal?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

A mother bought three dress for her triplets daughters(one for each) and put the dresses in the dark. One by one the girls come and pick a dress.
What is the probability that no girl will choose her own dress?