Answer:
-$19.
Step-by-step explanation:
From the question, we are given the following parameters or data and they are;
=> The Amount Kathy paid = $15.
=>The amount that Kathy was willing to = pay $ 18.
=> Price of new book= $ 37.
Therefore, we will make use of expression below to calculate the value for the Consumer surplus.
Consumer surplus = MP – AP -----(1).
Where MP = maximum price a consumer is willing to pay = $18 and AP = Actual price of a particular goods or commodity = $37.
Consumer surplus= $18 - $ 37 = -$19.