Henry Ernest Dudeney/Puzzles and Curious Problems/45 - Brother and Sister/Solution

by : $45$

 * Brother and Sister

Solution
The boy is $10$, and his sister is $4$.

Proof
You need only two of the given statements to solve this.

Let $b$ and $s$ be the ages of the brother and sister respectively.

We have:

The final two statements are redundant.