Dice are cubes where the sum of the numbers on the opposite faces is 7. Find the missing numbers a, b and c.

Draw two nets for the following polyhedron :

If in a polyhedron, number of faces = 20 and number edges = 30; the number of vertices is :

1. 12

2. 6

3. 8

4. 20

is the net of :

1. square pyramid

2. triangular prism

3. hexagonal pyramid

4. none of these