The Graph Shows the Total Sales in Thousand of Dollars $\frac{1}{2}$

Multiple Choice

The graph shows the total sales in thousand of dollars from the distribution of x thousand catalogs. Find the average rate of change of sales with respect to the number of catalogs distributed for the change in x.

-30 to 50

A) $\frac{1}{2}$
B) $\frac{3}{2}$
C) 2
D) 1