If a polyhedron has $12$ vertices and $8$ faces, then the number of edges of the polyhedron is

Which of the following is not a representation of Euler's formula?

A polyhedron has $5$ faces and $9$ edges. The number of vertices is 

In the following figure, there are three square gardening areas. The area of square $\mathrm{A}=81 {\mathrm{m}}^2,$ square $\mathrm{B}=49 {\mathrm{m}}^2.$ What is the area of the square $\mathrm{C}?$

In the figure below, area $(△ABC)=35 {\mathrm{cm}}^2$. The measure of $DC$ in $\mathrm{cm}$ is

The area of square $ABDC$ in the following figure in ${\mathrm{cm}}^2$ is

Area of the shaded region in the following figure is