A polyhedron has 8 vertices and 14 edges. How many faces must it have?

We know that

The Euler's formula state that, the number of vertices, minus the number of edges, plus the number of faces, is equal to two

V - E + F = 2

clear F

F=2-V+E

in this problem

V=8

E=14

F=?

so

F=2-8+14

F=8

the answer is

8 faces