Angela and Neil are going to the movies. They each bought a medium popcorn, and Neil got a small soft drink. Angela had a $15 gift certificate to put toward the cost, and Neil paid the rest, which came to $16.00. A movie ticket costs $9.00 and a medium popcorn costs $5.40. How much does a small soft drink cost at the theater?
a. $7.60 b. $2.20 c. $16.60 d. $3.00