Convert from pennyweight [troy] to libra [ancient Rome]

Unit Definition (pennyweight [troy])
The pennyweight is a unit of weight in the traditional troy system, equal to 24 grains or 1/20 troy ounce. One pennyweight is approximately 1.5552 gram.

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.