Respuesta :

A:  y = 60x

B: y = 55x + 40

60x  = 55x + 40
5x = 40
x = 8

y = 60*8 = 480

The cost for each plumber is the same, $480, after working 8 hours.
The cost is less for 5 hours working with plumber A.
60*5 = 300 ,  55*5 +40  = 315