JNU SSS 2011 Question 88: Perfect competition

The market for a good consists of 100 buyers and 50 sellers. Each seller has the same supply function, which is given by Supply $= 0$ if price $\leq 10$ $= p - 10$ if price $> 10$ Each buyer has the same demand function, which is given by Demand $= 0$ if price $\geq 20$ $= 20 - p$ if price $< 20$

Let the market equilibrium price be denoted by $p^*$. Then