The phone company NextFell has a monthly cellular plan where a customer pays a flat monthly fee and then a certain amount of money per minute used on the phone. If a customer uses 370 minutes, the monthly cost will be $205. If the customer uses 770 minutes, the monthly cost will be $405.

Let, fee and amount of money per minute used is P and m respectively.

Also, monthly fee is given by C.

The linear equation is given by :

( Here, x is the number of minutes )

Putting both the conditions in above equation, we get :

     .....1)

     .....2)

Subtracting 2 by 1, we get :

(770 - 370)m = 405-205

400m = 200

m = $0.5 .

So, c = 205 - 370×0.5

c = $20 .

Therefore, monthly fee and fee per minute used is $20 and $0.5 respectively.

Hence, this is the required solution.

the answers c

correct answer:

b.(19,-2)