Slove please

A cell phone carrier charges a fixed monthly fee plus a constant rate for each minute used. Part 1. In January, the total cost for 125 minutes was $62.5 while in February, the total cost for 400 minutes was $68. The constant charge for each minute used is: 0.02 O 0.03 0.04 Part 2. The fixed montly fee charged by the carrier is; fee = $