The Euler Formula states that for any polyhedron, if you add together the number of faces(F) and vertices(V), and subtract the number of edges(E), the answer is always two:
Use Euler's formula for this for a 3D figure. F + V = E + 2, where F is the number of faces, V is the number of vertices, E is the number of edges, +2! You have enough info to fill in the formula to find that the number of vertices is 6. Hoped I Helped