Final answer:
The selling price of the birdbath that includes a 42% markup on the selling price itself is $35. However, this price is not reflected in the available multiple-choice options, suggesting an error in the question or the options.
Step-by-step explanation:
To find the selling price of a birdbath with a retailer's markup, we must determine what 42% of the eventual selling price would be. This is because they want a markup based on the selling price itself, not just on the cost of the birdbath.
To represent the situation algebraically, let's let S be the selling price we are trying to find. The markup is 42% of S, so the markup is 0.42S.
The cost of the birdbath plus the markup will equal to the selling price: Cost of Birdbath + Markup = Selling Price, so in numbers it will be $20.30 + 0.42S = S.
To solve for S, subtract $20.30 from both sides to get 0.42S = S - $20.30. This simplifies to 0.58S = $20.30. Now divide both sides by 0.58 to isolate S: S = $20.30 / 0.58.
Calculating this gives us S = $35. Therefore, the selling price of the birdbath, including a 42% markup on the selling price, is $35, which is not an option in the multiple choice selection provided, indicating there may be an error in the question or options given.