Convert from quartern-loaf to arroba [Portugal]

Unit Definition (quartern-loaf)
The quartern-loaf is a traditional English unit of weight for bread. A quartern-loaf is made from a quartern of flour. The finished loaf usually weighs somewhere between 4 and 5 pounds (very roughly 2 kilograms).

Unit Definition (arroba [Portugal])
The arroba [Portugal] 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 Portugal and Brazil, the arroba traditionally equals 32.38 pounds (14.69 kilograms, but in recent years this has been "metrized" to be exactly 15 kilograms). 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."