Your friend asks you for a glass of water and you bring her 5 milimeter of water? is this more or less than what she was probably expecting? explain

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form

3. dark matter

empty space could also be a simple vacuum