<span>the answer is 32 miles per 1 gallon.</span>
Euler's formula is given by:
C + V = A + 2
Where,
C: number of faces
V: number of vertices
A: number of edges.
Clearing A we have:
A = C + V-2
Substituting values:
A = 21 + 14-2
A = 33
Answer:
the missing number is:
C.33