The following represents demand for widgets (a fictional product):
QD=650-4P-0.004M+4PR
where P is the price of widgets, M is income, and
PR is the price of a related (fictional) good, the wodget. Supply of widgets is determined by
QS=20+4P
Widgets are _________, and widgets and wodgets are _____________.
Select one:
a. a normal good; complements.
b. an inferior good; substitutes.
c. an inferior good; complements.
d. a normal good; substitutes.