Question

Look at the net of the polyhedron shown below.

Answer 1

The answer is 13

Euler's formula:
F + V - E = 2
F - number of faces
V - number of vertices
E - number of edges

We have:
F = 7
V = ?
E = 18

7 + V - 18 = 2
7 + V = 2 + 18
7 + V = 20
V = 20 - 7
V = 13