Respuesta :
In both cases, start with 0.
Every 15th customer includes #15, #30, #45, #60, etc.
Every 4th customer includes #4, #8, #12, #16, #20, #24, #28, #32, #36, #40, #44, #48, #52, #56, #60
#60 is the first customer to win both prizes.
Every 15th customer includes #15, #30, #45, #60, etc.
Every 4th customer includes #4, #8, #12, #16, #20, #24, #28, #32, #36, #40, #44, #48, #52, #56, #60
#60 is the first customer to win both prizes.