Final answer:
Rosa and her sister each ordered a meal for $8.70, doubling for two people to $17.40. A 20% gratuity of $3.48 was added, making the total cost $20.88.
Step-by-step explanation:
To calculate the total cost of Rosa and her sister's meal including the 20% gratuity, we first need to calculate the cost of their meal without the tip.
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- Each salad costs $7.20 and each soda costs $1.50.
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- Therefore, the cost of one person's meal is $7.20 (salad) + $1.50 (soda) = $8.70.
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- Since both Rosa and her sister had the same meal, we multiply the cost of one meal by 2: $8.70 × 2 = $17.40.
Next, we calculate the 20% gratuity:
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- To find the amount of the tip, we convert the percent to a decimal by dividing by 100: 20% = 0.20.
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- Then multiply the meal cost without the tip by the gratuity rate: $17.40 × 0.20 = $3.48.
Finally, we add the original meal cost to the gratuity to find the total cost:
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- Total cost = Meal cost + Gratuity
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- Total cost = $17.40 + $3.48 = $20.88.
The total cost of Rosa and her sister's meal, including a 20% gratuity, is $20.88.