Convert from obolos [Ancient Greece] to libra [ancient Rome]

Unit Definition (obolos [Ancient Greece])
The obolos [Ancient Greece] is a historic unit of weight or mass. The obol is a very small weight that originated as the weight of a tiny Greek coin. In ancient Greece the obolos was equal to 1/6 drachma, or roughly half a gram (8 grains).

Unit Definition (libra [ancient Rome])
The libra [ancient Rome] is a traditional unit of weight. The libra was the Roman unit from which the English pound is descended; the symbol "lb" for the pound comes from this unit. The Roman libra contained only 12 unciae (ounces) and was about 0.722 English pound. The word "libra" is sometimes used now for the kilogram, a much larger unit.