The monthly supply and demand for a particular bike is represented in the accompanying graph. The quantity is in thousands and the price is in hundreds of dollars. Use the graph to answer the following. The demand curve is red and the the supply curve is blue. 100 95 90 85 60 55 Price 50 (in hundreds) 45 40 35 30 25 20 -5 1-3 - 2 - 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Quantity (in thousands) 10- (a) Estimate the equilibrium quantity.