Suppose that a consumer spends a fixed amount of income per month on the following pairs of

Question:

Suppose that a consumer spends a fixed amount of income per month on the following pairs of goods:
a) Tortilla chips and salsa
b) Tortilla chips and potato chips
c) Movie tickets and gourmet coffee
d) Travel by bus and travel by subway
If the price of one of the goods increases, explain the effect on the quantity demanded of each of the goods. In each pair, which are likely to be complements and which are likely to be substitutes?