Krista has $13.20 in dimes and half-dollars. She has one-half as many dimes as half-dollars. How many of each coin does she have?

A) 12 half-dollars and 24 dimes

B) 12 half-dollars and 6 dimes

C) 6 half-dollars and 12 dimes

D) 24 half-dollars and 12 dimes