Peter, John and Anna had 60 stamps altogether. Peter had 30 stamps. John had 10 more stamps than Anna. How many stamps did Anna have?
In QOTW 20, we shared the basic concept of "Comparison of Quantity", one of the first multi-step heuristic concept introduced in Primary 2. This week, we would like to share a different variation of the "Comparison of Quantity" concept that involves "Part and Whole" concept.