Random Puzzles 

Workings

Hint
The answer is a whole number less than 10.

Answer
3.

Reasoning
We can multiply throughout by 12,
    X     X     X     X
    -  -  -  +  -  =  -
    X     2     4     12

to give:

   12 − 6X + 3X = X

        12 − 3X = X

             12 = 4X

              3 = X

As required.

Double-Checking
    3     3     3     3
    -  -  -  +  -  =  -
    3     2     4     12

    1 − 1.5 + 0.75 = 0.25

              0.25 = 0.25, which confirms that 3 is correct.

Workings

Hint
Look to the skies for the answer.

Answer
neerg.

These are the colours of the rainbow reversed.

Workings

Hint
It's not just the vowels (AEIOU) that have a problem.

Answer
H, S, and T.

Reasoning
It should read:

"Can you tell what is wrong with this paragraph? At first glance you may think that just the vowels have problems, but no! Three consonants also have problems, they have been replaced with the letter R, but which ones are they?"

Workings

Hint
A little algebra might help.

Answer
He will be 35 in 14 years.

Reasoning
He is currently 21.

If X is his current age, then:
  X = 14 +  X
           ———
            3
so

   2X = 14
  ———
   3

and

  2X = 42

So

  X = 21

He is currently 21 and his favourite book is currently 14 years old, when it is 28 years old (double its age) he will be 35.