Step by step please In 2001, X cost 3 and sold 400 units. That same year, a related good Y cost 10 and sold 200 units. In 2002, X still cost 3 but sold only 300 units, while Y rose in price to 12 and sold only 150 units. Other things the same, and assuming that the demand for X is a linear function of the price of Y, what was the cross-price elasticity of demand for X with respect to Y in 2001?