Imagine if your friend is 3ft, and he is scaled down into the drawing. If he's scaled down into the drawing, he would be 1 inch in the drawing. If your cat were 1.5ft, it would be half of your friend, so in the drawing it would be 0.5 inch. Now the table is 9ft, how many 3ft is in 9ft? That's 3 times of 3ft, so 1 inch would be multiplied 3 times, = 3 inches. Or there's a shortcut way in the pic.
