One cell phone company charges $0.05 per minute to talk and $20 to activate the line. Another cell phone company charges $0.20 per minute and $2.00 to activate the line. (Check description)

Question

When will these two costs be equal?

The cell phone plans cost the same if you talk for (answer here) minutes.

Answer 1

y = mx + b

y = (.05)x + 20

y = (.20)x + 2

(.05)x + 20 = (.20)x + 2

18 = .15x

x = 120 calls