One cell phone plan charges a flat monthly rate of $34.99 with extra charges of $0.10 per text message after the first 100 text messages. BODA (a) Choose letters that best represent the variables needed to write a formula that expresses the cell phone charges. Olet t denote the number of text messages. OLet t denote the number of text messages, P the type of plan, and the charge, in dollars. Olet t denote the number of text messages and the charge, in dollars. Olet C denote the charge, in dollars. (b) Write a formula to express the cell phone charges as a function of the number of text messages (assume that the number is at least 100). C = (c) Use functional notation to show the cost of the cell phone if you have 350 text messages. Use the formula from part (b) to calculate the cost if you have 350 text messages. (Round your answer to the nearest cent.) $ (d) Write a formula to express the cell phone charges, this time assuming that the number of text messages is less than 100. C =