Using Euler's formula, find the unknown number of faces.

Euler's formula for polyhedra states that V - E + F = 2, where V is the number of vertices, E is the number of edges, and F is the number of faces.

Given:
Vertices (V) = 520
Edges (E) = 612

We need to find the number of faces (F).

Substituting the given values into Euler's formula:
520 - 612 + F = 2
-92 + F = 2
F = 2 + 92
F = 94

Therefore, the unknown number of faces is 94.