$\"\"$

\

The demand curve is $\"\"$ .

\

Selling price is $\"\"$ .

\

Substitute $\"\"$ in the above equation.

\

$\"\"$

\

Consumer surplus of the commodity : $\"\"$ .

\

$\"\"$

\

$\"\"$

\

Let $\"\"$ .

\

Differentiate with respect to $\"\"$ .

\

$\"\"$

\

$\"\"$

\

Substitute $\"\"$ in the above equation.

\

$\"\"$

\

$\"\"$

\

Therefore, the consumer surplus is $\"\"$ .

\

$\"\"$

\

The consumer surplus is $\"\"$ .