The demand function is $p = 25 - x$ and the supply function is $p = 5 + x$. What is the consumer surplus at equilibrium?

Explanation

1. 01

   Equilibrium: $25 - x = 5 + x$, so $x_0 = 10$ and $p_0 = 15$.

2. 02

   $CS = \int_{0}^{10} (25 - x)\,dx - p_0x_0 = 200 - 150 = 50$ rupees.