Convert from military pace [double time] to feet [France]

Unit Definition (military pace [double time])
The length of a single step in marching (taken to be 30 inches for quick time or 36 inches for double time).

Unit Definition (feet [France])
A foot (plural: feet) is a non-SI unit of distance or length, measuring around a third of a metre. There are twelve inches in one foot and three feet in one yard.