The professor who came up with the question on Cheryl’s birthday wants us to guess her age now.

****SPOILER ALERT****

If you don’t want to spend your weekend wrecking brains our the brat Cheryl’s age, our Maths expert Wallace has the solution here. Enjoy!

Step 1: The product of all our ages is 144

A, B and C must be factors of 144. List down all the possibilities (shown in the table below). I did it systematically, with A the youngest child and C the eldest.

Step 2: Cheryl says “The sum of all our ages is the bus number of this bus that we are on.” and Bernard cannot guess. Since they know the bus number, the sum cannot be a unique number. From this we can eliminate many of the options, leaving:

2,8,9

3,4,12

3,6,8

and 4,4,9

Step 3: Cheryl says that her brothers have the same age. Of the possibilities, only 4,4,9 has two repeated numbers.

** Answer: Cheryl is 9 years old.**