Question

each month kadens phone charges a flat fee of $12 plus $0.05 per minute. his bill for last month was $18. how many minutes did luca talk on the phone last month? 100 600 120 350

Explanation:

Step1: Define the cost function

Let \( m \) be the number of minutes. The total cost \( C \) is the flat fee plus the cost per minute times the number of minutes. So, \( C = 12 + 0.05m \).

Step2: Set up the equation

We know the total bill \( C = 18 \). So, we set up the equation \( 12 + 0.05m = 18 \).

Step3: Solve for \( m \)

Subtract 12 from both sides: \( 0.05m = 18 - 12 = 6 \).
Then divide both sides by 0.05: \( m=\frac{6}{0.05}=120 \).

Answer:

120