100 points! a plumber charges a flat rate for coming to a person’s home and then charges an hourly rate for the amount of time he spends there. the amount of money he charges is given by the function equation c = 75 + 40t, where c is the amount he charges and t is the time he spends at a home in hours. what is the meaning of the vertical intercept in this equation? a. the plumber charges $40/h. b. the plumber charges $75/h. c. the plumber charges a flat rate of $40. d. the plumber charges a flat rate of $75.