Convert from dram to arroba [Spain]

Unit Definition (dram)
The dram is a unit of weight in the traditional avoirdupois system, equal to 1/16 ounce or 1/256 pound. One dram equals about 1.7718 gram. The word dram comes from a Latin weight unit, the dragma, and derives ultimately from the Greek drachme, meaning a handful. The word is usually spelled "drachm" in Britain and "dram" in the United States, but both spellings are pronounced "dram." The avoirdupois dram is sometimes abbreviated dr. av. to distinguish it from the apothecaries' dram.

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."