Final answer:
Part A: To find the discount, set up a proportion using the marked price and the dollar amount of the discount. Part B: Subtract the discount amount and add the sales tax to find the final cost of the tablet. Part C: Calculate the total cost for Laura by subtracting the discount and adding the sales tax to determine who pays the lower total cost.
Step-by-step explanation:
Part A: To set up a proportion to find the dollar amount of the discount (d), we can use the following equation:
x/100 = d/214.80
Where x represents the percentage discount. Since the discount is 15%, we can substitute x with 15:
15/100 = d/214.80
Simplifying the equation, we get:
d = (15/100) * 214.80
d = 32.22
Therefore, the dollar amount of the discount is $32.22.
Part B: To find the final cost of the tablet Spencer buys, we need to subtract the discount amount and add the sales tax. The final cost can be calculated as:
Final cost = Marked price - Discount + Sales tax
Final cost = 214.80 - 32.22 + (6/100) * (214.80 - 32.22)
Final cost = 182.58 + (6/100) * 182.58
Final cost = 182.58 + 10.95
Final cost = 193.53
Therefore, the final cost of the tablet Spencer buys is $193.53.
Part C: To compare the total cost for Laura, we need to calculate the discount and add the sales tax. The total cost for Laura can be calculated as:
Total cost = Regular price - Discount + Sales tax
Total cost = 226.50 - 0.30 * 226.50 + (8/100) * (226.50 - 0.30 * 226.50)
Total cost = 226.50 - 0.30 * 226.50 + (8/100) * 226.50 - (8/100) * 0.30 * 226.50
Total cost = 226.50 - 0.30 * 226.50 + 0.08 * 226.50 - 0.08 * 0.30 * 226.50
Total cost = 226.50 - 0.30 * 226.50 + 0.08 * 226.50 - 0.08 * 0.30 * 226.50
Total cost = 226.50 - 67.95 + 0.08 * 226.50 - 0.0216 * 226.50
Total cost = 226.50 - 67.95 + 18.12 - 4.8974
Total cost = 171.63 + 13.22
Total cost = 184.85
Therefore, Spencer pays the lower total cost of $193.53 compared to Laura's $184.85.