Consider the following demand function for widgets: Q_d=4500-20P- .001M+30P_R Is this a normal good or an inferior good? Is good R a substitute or a

Consider the following demand function for widgets: Q_d=4500-20P- .001M+30P_RIs this a normal good or an inferior good? Is good R a substitute or a complement?At what price is demand for widgets zero, if average income is $100,000 and the price of good R is $100?