The equation a = 640s gives the relationship between s square miles and a acres. pam owns 7.5 square miles of farmland. how many acres does she own?
a. 480 acres
b. 11.72 acres
c. 4,800 acres
d. 1.17 acres

Quantity of farmland owned by Pam = 7.5 square miles.
The other important information given in the question is the equation relating square miles and acres. Using that information, the answer to the question can be easily reached.
a = 640s
   = 640 * 7.5 acres
   = 4800 acres.
From the above deduction, we can conclude that the correct option among all the options that are given in the question is the third option or option "C".