A soccer ball is a polyhedron made from 20 regular hexagons and 12 regular pentagons. It has 60 vertices. Determine the number of edges on a soccer ball.

answer:  

\boxed {\frac{1}{5}}  

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solution-

60 *   \frac{1}{5}   = 12

90 * \frac{1}{5} = 18

75 * \frac{1}{5} = 15

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hence, the answer would be \boxed {\frac{1}{5}}