Which calculation should be completed first to solve this story problem? allister bought some sheet music. he bought 6 songs for $0.99 each and 1 book for $16.99. he paid $1.38 in sales tax. he gave the cashier $50. how much change should allister get? a. total cost of all the purchases b. total cost of 6 songs c. sum of the cost of 1 song, the book, and the tax d. the change