Read the little poem and answer its question if you can.

Question

The number of girls who do wear a watch
is double the number who don't.
But the number of boys who do not wear a watch
is double the number who do.

If I tell you the number of girls in my class
is double the number of boys,
Can you tell me the number I teach? Here's a clue:
More than 20; below 32!

Answer 1

27

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Number of girls is divisible by 3- lets say 3x
Number of boys is divisible by 3 as well- 3y
Number of girls is twice as the number of boys = 2*3y=6y
total number = 3y+6y=9y and is between 20 &32, this is 27 as the only number divisible by 9