Answer: Assuming you want an expression written: Let x equal each text message. Also, let C be equal to the total cost.
Plan A: 10 + 0.25x = c
Plan B: 25 + 0.15x = c
Plan A states that every month its company will charge $10 plus $0.25 per text message.
Plan B states that every month its company will charge $25 plus $0.15 per text message.