The following transactions are July activities of Bill's Extreme Bowling, Inc., which operates several bowling centers. If revenue is to be recognized in July, indicate the amount. a. Bill's collected $15,600 from customers for services related to games played in July. b. Bill's billed a customer for $600 for a party held at the center on the last day of July. The bill is to be paid in August. c. The men's and women's bowling leagues gave Bill's advance payments totaling $1,850 for the fall season that starts in September. d. Bill's received $1,500 from credit sales made to customers last month (in June).