Mrs. Williams is ordering designer cupcakes for her wedding.
Mrs. Williams pays a one-time fee of $55.
Mrs. Williams pays $6 for each cupcake ordered.
Which function can be used to find c, the total amount Mrs. Williams pays in dollars when k cupcakes are ordered?

a c = 6k + 55
b c = 61k + 6
c c = 55k + 6
d c = 6k + 61