Choice A is correct. It’s given that the window repair specialist charges for the first two hours of repair plus an hourly fee for each additional hour. Let represent the hourly fee for each additional hour after the first two hours. Since it’s given that is the number of hours of repair, it follows that the charge generated by the hourly fee after the first two hours can be represented by the expression . Therefore, the total cost, in dollars, for hours of repair is . It’s given that the total cost for hours of repair is . Substituting for and for into the equation yields , or . Subtracting from both sides of this equation yields . Dividing both sides of this equation by yields . Substituting for in the equation yields , which is equivalent to , or . Therefore, the total cost, in dollars, for hours of repair is .
Choice B is incorrect. This function represents the total cost, in dollars, for hours of repair where the specialist charges , rather than , for the first two hours of repair.
Choice C is incorrect. This function represents the total cost, in dollars, for hours of repair where the specialist charges , rather than , for the first two hours of repair, and an hourly fee of , rather than , after the first two hours.
Choice D is incorrect. This function represents the total cost, in dollars, for hours of repair where the specialist charges , rather than , for the first two hours of repair, and an hourly fee of , rather than , after the first two hours.