A mother's age is four times the sum of the ages of her three children. After 4 years, her age will be only double the sum of their ages. What is the mother's present age (in years)?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 40
In 4 years the mother grows 4 years older, but the sum of three children's ages grows by \(3\times4=12\) years.
Let the present sum of the children's ages be \(s\); mother's age \(=4s\)
After 4 years: \(4s+4=2(s+12)\)
\(4s+4=2s+24\), so \(2s=20\) and \(s=10\)
Mother's age \(=4\times10=40\) years