The "standalone" method of dealing with units treats units just like normal variables to be assigned-to and solved-for:
The following example shows typical usage of standalone units. The units are "miles" and "gallons", but they are really being used as simple variables:
> The number of miles per gallon is 21.
Let 'M' stand for "MILES"
Let 'G' stand for "GALLON"
So...
M
- = 21
G
Anything else?
> If there are 14 gallons, how many miles are there?
Solving for G:
14 = G
G = 14
G = 14
Solving for M:
M
- = 21
G
1
M - = 21
G
M = 21 G
M = 294
(Find M)
294 is HOW MANY MILES THERE ARE.
The standalone method can be used for simple problems, but it is usually too limited for most real-world problems involving units. Normally, one wants to freely combine units with numbers (scalars) and other units to specify measurements and systems of measurement.