The cost of the length of wood Marco buys depends on the price of the wood.
- The total cost in dollars of Marco's board is $15
Reasons:
The length of the wooden board Marco buys (quantity) = 12 feet
The cost of the board per foot, including tax (price) = $1.25
Let x represent the percentage of the tax applied to the total cost, and let y represent the cost before tax, we have;
Cost per foot, C₁ = 1.25 = y + x·y
The cost of 12 feet of the wooden board is given by the proportional relationship between cost, price and quantity as follows;
Cost = Price × Quantity
The cost of 12 feet of the wood is therefore;
Cost of 12 feet, C₁₂ = 12 × y + 12 × x·y = 12 × (y + x·y) = 12 × $1.25 = $15
The cost of 12 feet of wood = $15
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