2. A cellphone company offers the following plan: $20 per month buys 60 minutes. Additional time costs $0.40 per minute. a. [3 pts] Represent this plan mathematically by writing the total monthly cost, C, as a piecewise function of the number of calling minutes, t. b. [3 pts] Find and interpret the quantities C(30) and C(100). c. [3 pts] Graph y = C(t) for t values between 0 and 200 minutes. Indicate your scale on both the horizontal and vertical axes, and be sure to label what quantities each axis represents.