A cell phone company charges a $10 flat fee plus $0.05 per minute for minutes up to 600. For minutes over 600, the company

charges $0.15 per minute, in addition to the flat fee and the charges for the first 600 minutes.

Which function models the company's cell phone charges?!

In both the cases, the given total amount is given as:

T = 10 + 0.05 m (when minutes talked m < 600)

T = 40 + 0.15 k (when minutes talked k > 600)

Step-by-step explanation:

Here, the flat fee by the phone company = $10

The charge for each minute for first 600 minutes = $0.05

The per minute cost after 600 minutes = $0.15

Let us assume the number of minutes talked = m

Case 1: when the minutes talked is less than 600 minutes.

Total Charges = Flat Fee + 0.05 x (the minutes talked)

or, T = $10 + m ($0.05)

or T = 10 + 0.05 m (when m < 600)

Case 2: when the minutes talked is more than 600 minutes.

Let us assume the minutes talked over 600 = k minutes

Total Charges = Flat Fee + Charges for 600 minutes + 0.15 x (the minutes talked over 600)

or, T = $10 + 600 ($0.05) + k ($0.15)

or T = 10 + $30 + 0.15 k (when k > 600)

⇒ T = 40 + 0.15 k (when k > 600)

Hence, in both the cases, the given total amount is given as:

T = 10 + 0.05 m (when m < 600)

T = T = 40 + 0.15 k (when k > 600)