On the day of the performance of a certain play, each ticket that regularly sells for less than$10,00 is sold for half price plus $0.50, and each ticket that regularly sells for$10.00 or more is sold for half price plus$1.00. On the day of the performance, a person purchases a total of y tickets, of which x regularly sell for $9.00 each and the rest regularly sell for $12.00 each. What is the amount paid, in dollars, for the y tickets ？（）

A.7y-2x

B.12x-7y

C.

D.7y+4x

E.7y+5x