First we can subtract the sales tax so we are just working with what's left: $17 - $0.92 = $16.08. Then we multiply the price of the sandwiches by 2 for the number Corey bought: 5.25 x 2 = $10.50. Then subtract that amount from what you have left: $16.08 - 10.50 = 5.58. Then, take that amount and divide it by three drinks: $5.58 / 3(drinks) = $1.86 per drink. I don't see the table so I hope this answers the question well enough!:)
The length is 12, because if it's 9 inches wide it has two sides of 9 inches which is 18. Then subtract that from the intial value 42 to get 24. After, you divide 24 by 2 due to there being 2 sides of the box and 24 is the sum of both sides. Hopethis helps!