Paul's children
Paul is 32 years old. In ten years time, Paul's age will be the sum of the ages of his three sons. What do his sons' ages add up to now?
Age
11 to 14
Challenge level
Problem
Paul is 32 years old.
In ten years' time, Paul's age will be the sum of the ages of his three sons.
What do his sons' ages add up to now?
Student Solutions
Answer: $12$
Paul in ten years: $42$
Paul's children now: say $a, b, c$
Paul's children in ten years: $a+10, b+10, c+10$
$\therefore a+10+b+10+c+10=42\\
\Rightarrow a + b+c+30=42\\
\Rightarrow a+b+c=12$