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