how many faces are there in a prism with 24 edges

the relation between the edges , vertices and faces are as follows:
the number of edges = 3n
the number of vertices = 2n
the number of faces = n+2
where n is equal to the number of sides of polygon bases.
given : 3n = 24 ; i.e. n = 24/3 = 8
thus it is an octagonal prism.
the number of faces = n+2 = 8+2 = 10

hope this helps you