The demand function is $p = 50 - 3 x$ and the supply function is $p = x + 10$. What is the consumer surplus at equilibrium?

Explanation

1. 01

   The market clears at $x_0 = 10$, $p_0 = 20$.

2. 02

   $CS = \int_0^{10} (50 - 3 x)\,dx - 20 \times 10 = 350 - 200 = 150$.