Suppose f point c e (a, b) such that f (c) 0. is a differentiable function on la, b) and suppose f'(a) > 0> f (b). then there is a

One cell phone plan charges $20 per month plus $0.15 per minute used. a second cell phone plan charges $35 per month plus $0.10 per minute used. write and solve an equation to find the number of minutes you must talk to have the same cost for both calling plans.