Bot Winona and Takoda are shopping for a present for their mother. The chart shows several possible presents. There is no sales tax in the state where they live. Chart: Present: Power tools, Water skis, Jewelry. Cost ($): d, d + 15, d - 5. Discount (%): 15%, 25%, 10%. Total Paid: blank, blank, blank.

Question

a. Write two expressions in terms of d to show how much Winona and Takoda would pay in total if they buy their mother the set of power tools.
b. What does the expression 0.90(d - 5) refer to? How do you know? How else could this expression be written?
c. Choose a value for d that is greater than $25 and less than $100. Calculate the total cost of each of the possible presents for the value you chose. Then write a short paragraph telling Winona and Takoda which present they should buy and explaining why.

Answer 1

a. The total paid by Winona and Takoda for the set of power tools can be calculated as follows:
- For Winona: d - (0.15d) = 0.85d (after a discount of 15%)
- For Takoda: d - (0.15d) = 0.85d (after a discount of 15%)

b. The expression 0.90(d - 5) refers to a discount of 10% subtracted from the cost of the present d minus $5. We know this because 0.90 represents a discount of 10% (or 0.10), and (d-5) represents the cost of the present minus $5. Another way this expression could be written is 0.10(d - 5).

c. Let's choose d = $50.
For power tools: Total cost = d - 5 = 50 - 5 = $45
For water skis: Total cost = d + 15 = 50 + 15 = $65
For jewelry: Total cost = d - 5 = 50 - 5 = $45

Based on these calculations, Winona and Takoda should buy either the power tools or the jewelry. Both options cost the same, $45, which is the lowest price among the three presents. They should choose either of these presents because they provide the best value for their money.