It is entirely possible and his answer was correct. Question was phrased incorrectly, if the teacher wanted an answer “it is not possible” he should have said both pizzas were the same size.
A third option is that there is a third pizza eater who also ate 4/6th of their pizza and gave 2/6th up Marty in exchange for the 2/6th Marty didn’t eat.
It is entirely possible and his answer was correct. Question was phrased incorrectly, if the teacher wanted an answer “it is not possible” he should have said both pizzas were the same size.
A third option is that there is a third pizza eater who also ate 4/6th of their pizza and gave 2/6th up Marty in exchange for the 2/6th Marty didn’t eat.
Or yeah maybe it was a larger pizza.