### Brain Teasers

# Time does fly!

Five years ago, Anthony was three times as old as his sister. Now he is only twice as old. How old are Anthony and his sister?

### Answer

Anthony is 20 and his sister is 10. Five years ago he was 15 and she was 5.Hide Answer Show Answer

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## Comments

Five years ago, Anthony was three times as old as his sister. Now he is only twice as old. How old are Anthony and his sister?

let a represent Anthony's age, then s represent the sister

First Statement:

a - 5 = (s - 5) * 3

a = (s - 5) * 3 + 5

Second Statement:

a = s * 2

Combination:

2s = (s - 5) * 3 + 5

2s = (s - 5) * 3 + 5

2s = 3s - 10

-s = -10

s = 10

Therefore, Anthony's age is 20 and his sister's is 10.

let a represent Anthony's age, then s represent the sister

First Statement:

a - 5 = (s - 5) * 3

a = (s - 5) * 3 + 5

Second Statement:

a = s * 2

Combination:

2s = (s - 5) * 3 + 5

2s = (s - 5) * 3 + 5

2s = 3s - 10

-s = -10

s = 10

Therefore, Anthony's age is 20 and his sister's is 10.

Thanks Sane... I messed up my own figures for how to do that and ended up substituting in instead >.

I just thought it through in my head. I have seen one similar to this before.

hummm... :?

Ha ha..i guessed and got it right!

I m not sure that this 1 would be in the math catergory... i don't no y, but I dont think this is the appropriate catergory for this teaser.

we did millions of these in my math class this year so i got it right away

nice teaser

yoshinode-i guess this could be in the logic category, but i think it belongs in the the category it's in

nice teaser

yoshinode-i guess this could be in the logic category, but i think it belongs in the the category it's in

That was on my eighth grade mat test, when we were supposed to use variables. So, I got it

Everyone seems to have gotten the answer right, so what is the Correction?

I would get only partial credit. Too eager to find the answer.

I would get only partial credit. Too eager to find the answer.

Just gotta be methodical, raising the sister's age by 1 every attempt.

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