To find the equation that represents the total charge \( y \) for the delivery of \( x \) cookies, we can start by analyzing the given information.
Given Data:
- For 12 cookies, the total charge is $20.00.
- For 18 cookies, the total charge is $27.50.
- There is a $5 delivery fee.
Setting Up the Equations:
Let \( c \) be the cost per cookie.
The total charge can be expressed as: \[ y = cx + 5 \]
From the first data point:
- For 12 cookies: \[ 20 = 12c + 5 \] Subtracting 5 from both sides: \[ 15 = 12c \] Dividing by 12: \[ c = 1.25 \]
From the second data point:
- For 18 cookies: \[ 27.50 = 18c + 5 \] Subtracting 5 from both sides: \[ 22.50 = 18c \] Dividing by 18: \[ c = 1.25 \]
Conclusion:
We have confirmed that the cost per cookie \( c \) is indeed $1.25.
Final Equation:
Now, substituting the value of \( c \) back into the total charge equation: \[ y = 1.25x + 5 \]
Thus, the equation that represents the total charge in dollars \( y \) for the delivery of \( x \) cookies is: \[ \boxed{y = 1.25x + 5} \]