Scenario 4.3: The Demand for Erasers (Q) Is Given as Follows

Scenario 4.3:
The demand for erasers (Q) is given as follows:
Q = 240 - 4Pe + 2I + Pb + A
where Pe is the price of erasers
I is the level of income
Pb is the price of another good
A is the level of advertising
Suppose that Q = 240, Pe = 10, Pb = 10, and A = 2.
-Given the information in Scenario 4.3, erasers and good b, are:

A) substitutes.
B) complements.
C) completely unrelated.
D) normal.
E) inferior.