Use euler’s formula to find the number of edges in a polyhedron with seven faces: two pentagons and five rectangles.

We know that

Euler's formula states that Number of Faces plus the Number of Vertices (corner points) minus the Number of Edges is always equals 2

F+V-E=2
in this problem
F=7
V=2*5+5*4---> 30> (two pentagons and five rectangles)
E=?
E=F+V-2
E=7+30-2
E=35

the answer is
the number of edges is 35