Using Euler's Formula, the number of faces is given by: 8.
It states that the number of vertices, edges and faces is related by the following equation:
V - E + F = 2.
In this problem, the parameters are given as follows:
E = 15, V = 9.
Hence the number of faces is given by:
V - E + F = 2.
9 - 15 + F = 2
F - 6 = 2
F = 8.
More can be learned about Euler's Formula at https://brainly.com/question/12943884
#SPJ1