Convert from hundredweight [long, UK] to arroba [Spain]

Unit Definition (hundredweight [long, UK])
The hundredweight is a traditional unit of weight equal to 1/20 ton. The hundredweight is the English version of a commercial unit used throughout Europe and known in other countries as the quintal or the zentner. In general, this unit is larger than 100 pounds avoirdupois, so to fit the European market the hundredweight was defined in England as 112 pounds avoirdupois (about 50.8023 kilograms) rather than 100 pounds. This definition apparently dates from about the middle of the 1300's. The British hundredweight was divided into 4 quarters of 28 pounds, 8 stone of 14 pounds, or 16 cloves of 7 pounds each. To distinguish the two hundredweight units, the British version is often called the long hundredweight and the American is called the short hundredweight or cental.

Unit Definition (arroba [Spain])
The arroba [Spain] is a traditional unit of weight in Spain and Portugal, equal to 1/4 quintal. However, the Spanish and Portuguese quintals are of different sizes. In Spain, the arroba equals 25.36 pounds (11.50 kilograms); arrobas of very similar sizes were established in the Spanish speaking countries of Latin America. The arroba has also been used as a metric unit equal to exactly 15 kilograms. The name of the unit comes from ar rub', Arabic for "the quarter."