I've been stumped trying to figure out how to solve this question and I've received conflicting advice. I'm wondering which is correct, and how do actually go about solving this question.

"Let G be a simple graph withmedges andnvertices. How many different subgraphs with n vertices does G have?"

I'm given the following equation for assistance:

If is a graph (directed or undirected), then is called a subgraph of G if and , where each edge in is incident with vertices in