IKMC 2027 - Grades 3-4 - Self-study SET 1 - Thematic Batch 3 Question 24

Peter shares a chocolate bar with his sister and brother. First he breaks off a row of 5 pieces for his older sister. Then he breaks off a row of 7 pieces for his younger brother, as shown.
How many pieces were in the original bar?
Diagram labels: “Chị gái” means older sister; “Cậu em” means younger brother.