Puzzle 129
Alex's child, Drew, is exactly one fifth of Alex's age. In 21 years, Alex will be exactly twice Drew's age. How old is Drew now?
Billie is exactly seven times the age of his child, Glen. In 8 years, Billie will be three times the age of Glen. How old is Glen now?
Puzzle Copyright © Kevin Stone
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Hint
A little bit of algebra might help.
Answers
Drew is 7 years old.
Glen is 4 years old.
Answer #1
The first question involves Drew (D) and Alex (A).
Drew is currently one fifth of Alex's age, so:
(1) A = D x 5
In 21 years, Alex will be twice their age, so:
(2) A + 21 = (D + 21) x 2
Using (1) in (2) gives:
A + 21 = (D + 21) x 2
5D + 21 = (D + 21) x 2
5D + 21 = 2D + 42
3D = 21
D = 7
So Drew is 7 (and Alex is 35).
Answer #2
The second question involves Glen (G) and Billie (B).
Billie is exactly seven times the age of Glen:
(3) B = G x 7
In 8 years, Billie will be three times the age of Glen, so:
(4) B + 8 = (G + 8) x 3
Using (3) in (4) gives:
B + 8 = (G + 8) x 3
7G + 8 = (G + 8) x 3
7G + 8 = 3G + 24
4G = 16
G = 4
So Glen is 4 (and Billie is 28).
Puzzle 130
Which of the shapes is identical to the first one?
There might be more than one.
Puzzle Copyright © Robert A. Hartmann
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Try to rotate them around in your head, but watch out for mirror images.
Puzzle 131
In the sentence below, the three missing words are anagrams of each other:
When I pressed ? on the scales, it brought a ? to my eye, as a piece of metal stuck in my finger. I didn't ? this as a good experience.
Puzzle Copyright © Kevin Stone
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Hint
The answers have 4 letters.
Answer
When I pressed TARE on the scales, it brought a TEAR to my eye, as a piece of metal stuck in my finger. I didn't RATE this as a good experience.
Puzzle 132
What is made from nothing …
… yet you can see it?
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Hint
Think about it carefully.
Answer
A hole, or a shadow.
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