In 2001, X cost $4 and sold 400 units. That same year, a related good Y cost $10 and sold 200 units. In 2002, X still cost $4 but sold only 350 units, while Y rose in price to $ 14 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 crossprice elasticity of demand for X with respect to Y in 2001