Answer:
E = 18
Step-by-step explanation:
Euler's formula for polyhedra states
F + V = E + 2 ( F is faces, V is vertices, E is edges )
Here F = 8, V = 12 , then
8 + 12 = E + 2 , that is
20 = E + 2 ( subtract 2 from both sides )
18 = E
Then number of edges is 18