Seems the answer required but surely an error as 80 penny farthings were equivalent 100 old pence and there were 240 pence to the pound, when farthings were legal tender pre 1961.
Has to be an error as farthings no longer legal tender. Never have 80 penny farthings made a pound but at one time 192 penny farthings did make a pound.
Surely it’s 80 pennies +
80 farthings which equal 20 pence.So although mixing both decimal and pre decimal currency I think that’s how it’s den arrived at.