But others insisted the answer was 65, based on the algebra working: "X - 19+17 = 63. X = 65."
The equation was also put forward by Lewis Hadlow, who concluded that it was "quite hard for a Year 2."
Bloxham further confused the debate by adding that someone had shared an answer of 46 on a Facebook forum for teachers.
"You ignore the 19 - they are a red herring presumably. So 63 - 17 = 46", they wrote.
The correct answer is in fact 65. By subtracting the 17 people who had just boarded the train from the current number of passengers, 63, you are left with 46.
You then add the first lot of 19 passengers who exited the train, reaching an answer of 65.
- nzherald.co.nz