Question

cell phone company Y charges a $10 start-up fee plus $0.10 per minute, x. cell phone company Z charges $0.20 per minute, x, with no start-up fee. which function repesents the difference in cost between company Y and company Z?

Answer 1

Company Y: 
Cost = C
# of minutes = x
C = 0.10x + 10

Company Z:
Cost = c
# of minutes = x
c = 0.20x

Difference in cost = c - C
c - C = 0.20x - (0.10x + 10)
c - C = 0.10x - 10

Hope this helps! :)