Answer: 9 centimeters
Explanation:
Hi, to answer this question we have to apply the same ratio applied to find the height in centimeters of the door.
12ft/36cm = 9ft/x cm
12/36= 9/x
x = 9/ (12/36)
x =27cm
Using the value of the window's wide instead of the door's height.
12/36 = 3/x
x = 3 / (12/36)
x = 9cm
Feel free to ask for more if needed or if you did not understand something.