Question

Please answer the question and show work please.

Answer 1

Answer: 9

Step-by-step explanation

To have AB perpendicular to CD, we need to have angles AEF and FED add up to 90 degrees.

(angle AEF) + (angle FED) = 90

(5x-7) + (7x-11) = 90

12x - 18 = 90

12x = 90+18

12x = 108

x = 108/12

x = 9