1. The problem involves four clusters of three numbers each, connected by lines. Each cluster forms a triangle with three numbers. 2. From the first cluster, numbers are 8, 7, and 20. For the second cluster, numbers are 4, 3, and 12. 3. Third cluster (labeled "2.") has numbers 7 (top), an unknown number (bottom-left), and 18 (right). 4. Fourth cluster (labeled "3.") has numbers 7 (top), 7 (bottom-left), and 37 (right). 5. We need to find the missing number in the third cluster, likely using the pattern from the other clusters. 6. Observing the first cluster: sum of top and bottom-left numbers is $8 + 7 = 15$. The number at the right heart is 20, which is $15 + 5$. 7. Observing the second cluster: sum of 4 and 3 is $7$. The right heart number is 12, which is $7 + 5$. 8. From these two clusters, it seems the right number equals the sum of the other two plus 5: $$ Right = (Top + BottomLeft) + 5 $$ 9. Applying this to the third cluster (labeled "2."): Let the missing number be $x$. Then, $18 = 7 + x + 5$. Simplifying, $$ 18 = 7 + x + 5 $$ $$ 18 = x + 12 $$ $$ x = 18 - 12 = 6 $$ 10. So, the missing number in the third cluster is 6. 11. For completeness, check the fourth cluster (labeled "3.") where numbers are 7, 7 and 37. Sum of 7 and 7 is 14. Adding 5 gives $14 + 5 = 19$, but right number is 37. 12. The previous pattern doesn't fit the last cluster, so maybe another pattern applies there. 13. Check if the right heart is the product plus a constant: $7 imes 7 = 49$, but 37 is less than 49. 14. Try difference: $49 - 12 = 37$. So maybe right heart = product - 12. 15. To summarize final results: - Third cluster missing number: 6 - Derived patterns: Cluster 1 & 2: Right number = sum of top and bottom-left + 5 Cluster 4: Right number = product of top and bottom-left - 12 Final answer: missing number in third cluster is **6**.