Gillian purchased 25 books at the library book sale. Each hardcover book cost $1.50, and each paperback book cost $0.50. Gillian spent a total of $26.50. The book costs can be represented by the system of equations below.
h + p = 25
1.50h + 0.50p = 26.50

How many paperback books did Gillian buy?
11
12
13
14