IKMC 2021 - Grades 7-8 - Set 2 - Self-study Question 11

A rectangular chocolate bar is made of equal squares. Neil breaks off two complete strips and eats their 12 squares. Later Jack breaks off one complete strip and eats its 9 squares. How many squares remain?

Source note: the source does not specify that Neil’s strips are parallel. Use that intended reading for the listed choices.