Explanation:

I.x² – 17x + 72 = 0
x² – 9x – 8x + 72 = 0
x(x – 9) – 8 (x – 9) = 0
(x – 8) (x – 9) = 0
x = 8, 9
II. y² – 27y + 180 = 0
y² – 12y – 15y + 180 = 0
y(y – 12) – 15 (y – 12) = 0
(y – 15) (y – 12) = 0
y = 15, 12
y > x