To find the equation that represents the total charge \(y\) for a delivery of \(x\) cookies, we need to identify the cost per cookie and the fixed delivery fee.
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Identify the delivery fee: The bakery charges a $5 delivery fee.
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Calculate the cost per cookie: Using the total charges for the deliveries provided:
- For 12 cookies at $20: \[ \text{Cost of cookies} = 20 - 5 = 15 \] Therefore, the cost per cookie is: \[ \frac{15}{12} = 1.25 \]
- For 18 cookies at $27.50: \[ \text{Cost of cookies} = 27.50 - 5 = 22.50 \] Therefore, the cost per cookie is: \[ \frac{22.50}{18} = 1.25 \] Both calculations confirm that the cost per cookie is $1.25.
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Write the equation: The total charge \(y\) consists of the delivery fee plus the cost of the cookies: \[ y = 1.25x + 5 \]
Thus, the equation that represents the total charge in dollars \(y\) for a delivery of \(x\) cookies is:
\[ \boxed{y = 1.25x + 5} \]