Glenda makes an online purchase of 4 picture frames for $12.95 each and 4 mats for $5.89 each. The site says that taxes paid by the customer are 6.5% of the total purchase price. Shipping charges are based on the following table: Amount of Purchase Standard Shipping Express Shipping up to $50 $5.10 $7.00 $50 up to $100 $6.35 $8.20 $100 up to $200 $7.80 $11.60 $200 and over $10.50 $16.45 Glenda selects express shipping for her purchase and the company bills her credit card $91.86 for the total of the online purchase. Determine if Glenda has been billed correctly for her purchase. a. Glenda has been billed correctly. b. Glenda has not been charged enough for her purchase. c. Glenda has been over charged by $3.40 for her purchase. d. Glenda has been over charged by $3.80 for her purchase.