Jane Has 17 Phone Cards Worth Either $20 or $15

Multiple Choice

Jane has 17 phone cards worth either $20 or $15. How many of each does he have if the phone cards total $315?

A) twelve $20 cards and five $15 cards
B) five $20 cards and twelve $15 cards
C) eleven $20 cards and six $15 cards
D) fifteen $20 cards and one $15 cards