The number of vertices in a pyramid is equal to the number of faces. How many vertices does a regular pyramid with 40 edges have?

There would be 21 vertices.

Step-by-step explanation:

Remember that the Euler's formula states that

V - E + F = 2

According to the problem V = F, so

2V - E = 2

and E = 40. Therefore

2V - 40 = 2 and, V = 21, and there would be 21 vertices.