Seven Dwarfs
The Seven Dwarfs have seven different birthdays. How old can they be?
The Seven Dwarfs were born on the same day, in seven consecutive years. The ages of the youngest three add up to $42$ years. What do the ages of the oldest three add up to?
Answer: 54
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Suppose the youngest dwarf is $x$ years old.
Sum of the ages of the youngest three is $x+(x+1)+(x+2)=3x+3$
Sum of the ages of the oldest three is $(x+4)+(x+5)+(x+6)=3x+15$.
We know that $3x+3=42$, so $3x+15=42+12=54$, so the ages of the oldest three of the Seven Dwarfs add up to $54$.
Patterns in the numbers
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![Seven Dwarfs Seven Dwarfs](/sites/default/files/styles/large/public/thumbnails/content-id-6770-seven%252520dwarfs.png?itok=bnF3vGEM)
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![Seven Dwarfs Seven Dwarfs](/sites/default/files/styles/large/public/thumbnails/content-id-6770-seven%252520dwarfs%2525202.png?itok=s3HymVEK)