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IKMC 2021 - Grades 11-12 - Self-study Question 25

IKMC · IKMC 2021 - Grades 11-12 - Self-study

Question 25

The pictured solid has 12 regular pentagonal faces; its other faces are equilateral triangles or squares. Each pentagon is surrounded by 5 squares, and each triangle by 3 squares. John writes 5 on each pentagon,1 on each triangle, and−1 on each square. What is the total?

Question illustration
  1. 20
  2. 50
  3. 60
  4. 80
  5. 120