Q:A graph has 12 edges and 6 nodes, each of which has degree of 2 or 5. How many nodes are there of each degree?
let m = the amount of edges, then $$ 2m = \sum_{v\in V} deg(V) $$
from here we can see that the right side equation will = 2(12) = 24
the only way we can get 24 from 6 nodes of either degree 5 or 2 is:
4 nodes of degree 5 and 2 nodes of degree 2
am I correct in my work?