The extended demand function of good X is: QDX = 1200 - 10 PX + 20 PY + 0.25 M where: QDX = quantity demanded of good X, PX = Price of good X, M = Average consumer income, and PY = Price of related good Y (related in consumption to good X). If M = 20,000, PY = 10, and PX = 400; then QDX = __? and if M = 20,000, PY = 10, and PX = 420 then QDX