Short Answer 
To calculate the total cost for frames and mats, first determine their individual costs, resulting in $75.36 before tax. After applying a tax of 6.5% and including additional fees, the final amount comes to $88.46, leading to an overcharge of $3.40.
Step 1: Calculate the Total Cost of Frames and Mats
Start by determining the total cost for both the frames and mats individual purchases. You will do this by multiplying the unit price of each item by the number of pieces purchased. The calculations should be:
- Frames: $5.89 x 4 = $23.56
- Mats: $12.95 x 4 = $51.80
Step 2: Add Up the Total Before Tax
Next, sum the costs of frames and mats to find the total amount before tax. This step is crucial as it sets the baseline for calculating the applicable tax on the purchase:
- Total before tax: $23.56 + $51.80 = $75.36
Step 3: Calculate the Final Amount After Tax and Fees
Finally, multiply the pre-tax total by the tax rate to find the tax amount. Add both the tax and any additional fees to get the final amount. Here’s how the calculations proceed:
- Tax: $75.36 x 6.5% = $4.90
- Final amount: $75.36 + $4.90 + $8.20 = $88.46
- Overcharge: $91.86 – $88.46 = $3.40