Random Puzzles 

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.

Workings

Hint
How many days separate the two dates?

Answer
18 days.

Reasoning
There are 140 days between the two dates, and these 140 days are split in the following way:

   4 x Answer | 50 days | Answer

We already know about 50 days, so we have to split the remaining 90 days into the ratio 4:1, which is 72:18.

   72 days | 50 days | 18 days

Workings

Hint
Both words begin with the letter B.

Answer
Brainy and binary.

Workings

Hint
Try saying the letters out loud.

Answer
E.

These are letters which all sound the same, bee, see, dee, ee, etc. All depending on how you pronounce Z (zee or zed), you can include this.