Ade and Uche can do a piece of work in 18 days. Ade can do it alone in x days, whilst Uche takes 15 days longer to do it alone. Which of the following equations describes x?

• A.x² - 5x - 18 = 0
• B.x² - 20x + 360 = 0
• C.x² - 21x - 270 = 0
• D.2x² + 42x - 190 = 0