Astate department of public safety added 1313x2 + 5x miles of highway to connect cooltown and bragville. it cost the department 3x2 – 9x thousand dollars to complete each mile of interstate. which expression shows the total cost, in thousands of dollars, of creating this highway? a) x^4 + 12x^3 – 45x^2 b) x^4 – 45x^2 c) x^4 + 15x^3 – 48x^2 d) 9x^4 – 12x^3 – 45x^2