Suppose the demand function for some good X is given by QDx = 1000 - 5Px + 3Py + 12M, where QDx is the quantity of x demanded, Px is its price, Py is the price of good Y, and M is average consumer income. This good is normal and goods X and Y are substitutes. [Hint: Determine the sign of the income and cross-price elasticity]I am supposed to determine if this question is true or false and explain why. How might I go about determining this?