SOLUTION: Jim gave one-third of his jellybeans to Jack, ate two-thirds of the remainder, and had 12 left over. How many jellybeans did he have originally?

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Question 193650: Jim gave one-third of his jellybeans to Jack, ate two-thirds of the remainder, and had 12 left over. How many jellybeans did he have originally?
Found 2 solutions by josmiceli, Edwin McCravy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let n = the number he had originally
given:
The amount he gave to Jack = %281%2F3%29%2An
The remainder = %282%2F3%29%2An
Two-thirds of the remainder = %282%2F3%29%2A%282%2F3%29%2An
------------------
The amount he ate plus the left over beans has to
equal %282%2F3%29%2An, so
%282%2F3%29%2A%282%2F3%29%2An+%2B+12+=+%282%2F3%29%2An
Multiply both sides by 9
4n+%2B+9%2A12+=+6n
4n+%2B+108+=+6n
2n+=+108
n+=+54
He originally had 54 jelly beans
check answer:
He gave Jack %281%2F3%29%2A54+=+18
He had left %282%2F3%29%2A54+=+36
He ate %282%2F3%29%2A36+=+24
There were 12 left over
Jack's + what he ate + left overs +
18+%2B+24+%2B+12+=+54
OK

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
Edwin's solution:
Jim gave one-third of his jellybeans to Jack, ate two-thirds of
the remainder, and had 12 left over. How many jellybeans did he
have originally?

The 12 he had left over at the end was the other one-third of
what he had before eating the two-thirds.  So 12 was 1/3 of 
those he had before starting eating.  So he had 3x12 or 36 before
starting to eat.

So those 36 he had before starting eating was the other 2/3 of what
he had before giving the one-third to Jack.  So since 1/3 is half
of 2/3, then he gave Jack half of 36 or 18.  So before giving those
18 to Jack, he must have had 36+18 or 54.

---

Now we check:

Jim gave one-third of his jellybeans to Jack, 

So Jim started with 54 and gave 54*1/3 or 18 of them to Jack.

That means he only had 54-18 or 36 left.

Then Jim ate two-thirds of the remainder, 

That means he ate 2/3 of 36 or 24.

So he had 36-24 or 12 left.
  
So 54 is the correct answer.

No algebra necessary!

Edwin