The demand for good X is estimated to be Qxd = 5,000 - 5PX +3PY + 2M + AX, where PX is the price of X, PY is the price of good Y, M is income and AX is the amount of advertising on X. Suppose the present price of good X is $25, PY = $50, M = $30,000, and AX = 500 units. What is the own-price elasticity of demand for good X?