I would assume a Y is 9 inches long because someone wrote it that big.
It is: 9*4.5*3 = 121.5 cubic inches
2.286 cm
Yes, that's quite big.
25.4 mm = 1 inch 9 mm = 0.354 inch (rounded) That's a touch longer than 1/3 inch.
It is 9 inches wide.
9 inches x 9 inches = 81 one inch servings
y=x+9 y'=1 x+9=0 x=-9 y=-9+9 y=0
A number 9 haircut typically leaves the hair about 1 inch long.
A board that is 7.5 feet long is 7.5 x 12 = 90 inches long. You can (mathematically) make 10 blocks 9 inches long from 90 inches of material, but only if the blade of your saw has a width (kerf) of zero. In the real world, you'll get 8 blocks and a good bit of change sawing 9 inch blocks off a 7.5 foot board. For a saw kerf of 0.125 inches (1/8th of an inch), You'll have lost 1 inch in your cuts, and you'll get 8 of the 9-inch pieces with your leftover piece being 8 inches long.
y = 3x + y => x = 0then y = x - 9 => y = 0 - 9 = -9.
2 1/4 inch is 9/4 inch long pieces, so if pipe is 36 in long then 36/divided by 9/4 is 36 times 4/9 = 16 pieces
3x-y=9 y=3x-9