Answer:
Fewer study guides being sold.
Step-by-step explanation:
The textbook and the study guides are the material or the books which help the student in order to gain knowledge by going through or study the textbook as well as the guide.
The study guide and the textbooks are complements means that the study guide is the supplement the textbooks as the study guide has the solutions for the questions of the textbooks.
But when there is increase in the price of the textbooks, the demand for the study guides will be decrease as the textbooks will not be purchased by the students which result in fewer study guides being sold in the market.