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
