The image shows a Venn diagram with three sets: $C$, $B$, and $M$. The numbers within the diagram represent the elements in various regions corresponding to the intersections of these sets. Let's analyze the sets:

1. Set $C$ contains:

   • Only in $C$ (not in $B$ or $M$): $13$
   • In $C \cap B$: $5$
   • In $C \cap M$: $6$
   • In $C \cap B \cap M$ (the intersection of all three sets): $4$

2. Set $B$ contains:

   • Only in $B$ (not in $C$ or $M$): $20$
   • In $B \cap C$: $5$
   • In $B \cap M$: $2$
   • In $B \cap C \cap M$: $4$

3. Set $M$ contains:

   • Only in $M$ (not in $B$ or $C$): $30$
   • In $M \cap C$: $6$
   • In $M \cap B$: $2$
   • In $M \cap B \cap C$: $4$

In summary:

• The total number of elements in $C$: $13 + 5 + 6 + 4 = 28$
• The total number of elements in $B$: $20 + 5 + 2 + 4 = 31$
• The total number of elements in $M$: $30 + 6 + 2 + 4 = 42$

If you want any further details or have specific questions about the set relationships, feel free to ask!

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Here are some related questions for further understanding:

1. What is the union of all three sets $C \cup B \cup M$?
2. How many elements are common to both $B$ and $C$ but not in $M$?
3. What is the number of elements that belong to both $B$ and $M$?
4. What is the total number of elements present in the diagram?
5. How many elements belong only to $C$?

Tip: Venn diagrams are a great visual tool to analyze relationships between sets and identify intersections, unions, and differences.