Though imperial-system users don't mix units like that, it's not like "20 minutes 30 seconds", they just use fractions or decimals as appropriate. "20 and a half minutes" or "20.5 minutes". You'd just say "17.8 yards".
(Metric user here, with an appreciation for base 12)
nobody has a tape measure marked in decimal yards or decimal feet, so nobody is going to say 17.8 feet or 17.8 yards
sexagesimal system users also mix units like this: 2 hours, 10 minutes, and 5.2 seconds
same for larger units of time: 5 years, 2 months, and 12 days (which is an example units(1) can't hack)
You have: QuedraTim
You want: hour
* 1
/ 1
You have: QuedraTim
You want: minutes
* 60
/ 0.016666667
You have: TrinaTim
You want: minutes
* 5
/ 0.2
You have: DunaTim
You want: minutes;seconds
25 seconds
You have: QuenaTim
You want: hour
* 12
/ 0.083333333
You have: Grafut
You want:
Definition: gravity Tim^2 = 0.29558045 m
You have: QuedraGrafut
You want:
Definition: 12^4 Grafut = 6129.1562 m