How do i find 1/3 of 12

Which of the following represents a number squared is equal to twenty more than nine times that number ? a) x squared = 9x + 20 b) x squared = 20x + 9 c) x squared > 9 + 20x d) x squared = 9 + x + 20

How do i do this activity, is appreciated

What is not true about kl and mn? what is mn? (show your work)