Consider a market consisting of two farms producing same quality of wheat. The market demand curve and the market supply curve for rice are given by: 
q_D = 250 - p for 0≤p≤250  

= 0 for p > 250 

q_S = 150 + p for p ≥10 
= 0 for 0≤p<10 

What will be the equilibrium quantity? 

200

The correct answer is option 2: 200

Since at equilibrium price market clears, we find the equilibrium price by equating market demand and supply and solve for p.
250-p = 150+ p
100 = 2p
50 = p
Putting p=50 in either demand equation or supply equation, we get q = 200.