A dodecahedron has 20 vertices. How many edges does it have?

By definition, a regular dodecahedron has 12 pentagonal faces.So, Number of faces ($F$) = 12.Given, Number of vertices ($V$) = 20.We can apply Euler's polyhedron formula to determine the number of edges ($E$):
$$F+V-E=2$$
Substitute the values of $F$ and $V$:
$$12+20-E=2$$
$$32-E=2$$
$$E=32-2=30$$
Hence, a dodecahedron has 30 edges.