Vera orders some prints of photos that she uploaded to her computer. she orders 3 of the 5 x 7 prints for $0.89 each, 12 of the 4 x 6 prints for $0.15 each and 1 of the 8 x 10 prints for $2.99. she also orders a photo album for $8.69. vera pays taxes that are 7% of the total purchase price. her shipping charges are based on the following table: amount of purchase standard shipping express shipping up to $20 free $3.50 $50 up to $100 $6.35 $8.20 $100 up to $200 $7.80 $11.60 $200 and over $10.50 $16.45 vera selects standard shipping and the company bills her credit card $20.78 for the total of the online purchase. determine if vera has been billed correctly for her purchase. a. vera has been billed correctly. b. vera has not been charged enough for her purchase. c. vera has been over charged by $1.13 for her purchase. d. vera has been over charged by $3.50 for her purchase.