Calculate the following.

If a polyhedron has $24$ edges and $10$ faces, how many vertices does it have?

 

If a polyhedron has $10$ faces and $7$ vertices, how many edges does it have?

Look at the following figures and verify Euler's formula, where $F, V$ and $E$ stand for number of faces, number of vertices and number of edges respectively.

Look at the following figures and verify Euler's formula, where $F, V$ and $E$ stand for number of faces, number of vertices and number of edges respectively.

Look at the following figures and verify Euler's formula, where $F, V$ and $E$ stand for number of faces, number of vertices and number of edges respectively.

Look at the following figures and verify Euler's formula, where $F, V$ and $E$ stand for number of faces, number of vertices and number of edges respectively.

Look at the following figures and verify Euler's formula, where $F, V$ and $E$ stand for number of faces, number of vertices and number of edges respectively.

How many faces are there in a cube?

How many faces are there in a tetrahedron?