Twenty pounds converts to 9.07 kilograms. The metric system represented an attempt to bring standardization and sense to the imperial system, which had been in use throughout the British Empire and elsewhere. However, problems arose from a lack of standardization.
The metric system uses natural objects and the decimal system to make measurements easier. For example, a liter of water was defined to weigh 1 kilogram and measure 1 cubic deciliter. The boiling point of water was defined as 100 degrees Celsius, and the freezing point was set at 0 C. Because of the sense involved in this measurement system, it is the standard throughout most of the world.