SOLUTION: A boy is 4 years old and his sister is three times as old as he is. When the boy is 12 years old, how old will his sister be?

Question 100568: A boy is 4 years old and his sister is three times as old as he is. When the boy is 12
years old, how old will his sister be?
Answer by Edwin McCravy(20056) (Show Source): You can put this solution on YOUR website!


A boy is 4 years old and his sister is three times as old as he is. When the
boy is 12 years old, how old will his sister be?

>>...A boy is 4 years old and his sister is three times as old as he is...<< 

That tells us that the sister is three times 4, or 12.  She is therefore 8 
years older than her 4-year-old brother.

>>...When the boy is 12 years old, how old will his sister be?...<<

When the boy is 12, his sister will be 8 years older than him, so she'll be 20.

You don't need any algebra for that.  You just think it out. 

Edwin

RELATED QUESTIONS
A boy is 4 years old and his sister is three times as old as he is. When the boy is 12... (answered by darq)
A boy is 4 years old and his sister is three times as old as he is. When the boy is 12... (answered by Edwin McCravy)
5. A boy is 5 years old and his sister is three times as old as he is. When the boy is... (answered by josgarithmetic,t0hierry)
If a boy is 5 years old. and his sister is 3 times his age. how old will the sister be... (answered by lenny460)
A boy is 5 years old and his sisters is twice as old. When the boy is 8 years old, how... (answered by bobdabuildr)
A boy is 17 years old and his sister is twice as old. When the boy is 23 years old, what... (answered by Maths68,Hankmanscott)
Joshua is 12 years old and his sister is three times as old as he. When Joshua is 23... (answered by lynnlo,Alan3354)
a boy is 5 years old, and his sister is twice as old. when the boy is 8 years, what will... (answered by ichudov)
A boy is 17 years old and his sister is twice as old. When the boy is 23 what will be the (answered by ewatrrr)