Convert from keg [nails] to arroba [Spain]

Unit Definition (keg [nails])
The keg [nails] is a traditional unit of weight for nails. A keg of nails weighs 100 pounds and thus has a mass of about 45.359 kilograms.

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."