A cell phone carrier charges a fixed montly fee plus a constant rate for each minute used. In January, the total cost for 250 minutes was $55 while in February, the total cost for 150 minutes was $53. Choose the formula below which gives the function C(x) representing the monthly cost, in dollars, of a cell phone using x minutes.

Select the correct answer below:

C(x)=0.02x+50

C(x)=−0.02x+56

C(x)=0.05x+28

C(x)=−0.05x+78