We know that, Euler's formula for any polyhedron is, F + V - E = 2
Given, faces (F) = 12, vertices (V) = 20
Now, on putting the value of F and V in the Euler's formula, we get 12 + 20 - E = 2
⇒ 32 - E = 2 ⇒ 32 - 2 = E ⇒ E = 30
Hence, the number of edges = 30