Question

John shared a 12 Slice Pizza equally with two of his friends after his friend ate their share he ate two thirds of his chair what fraction of the pizza is still left

Answer 1

Since "chair" probably means "share", John will have 2 2/3 slices of pizza left. 
The 12 slice pizza is split between 3 people, so each person gets 4 slices. John only eats 2/3 of his 4 slices, and 2/3 of 4 is 2 2/3.