To produce sausage formulations, packers use vegetables, apples, and
soy concentrate. The manufacture uses 3% soy in final saugage mass.
Water is added to the formulation as ice. The final sausage must
contain 15% protein, 60% moisture, and 25% fat.
The ingredients contain the following:

Ingredients          Protein %          Moisture %      Fat%
vegetables            20                   67            13
apples                10                   40            50
Soy                   90                   7             0

How much of each ingredient should be combined to make 600kg of
sausage emulsion?

Ice, water, moisture, soy  .....Kindda confusing . Please clarify !

Hey, the question actually makes a lot of sense. It's the answer that
doesn't make sense. You have to set up three equations:
.2x+.1y+.9z=.15
.67x+.4y+.7z=.6
.13x+.5y=.25

The answer is
x=.748
y=.305
z=-.034
where x= the amount of vegetables, y=amount of apples, and z=amount of
soy. I.e., if you multiply the values above by 600kg, you'll get how
much you need of each. So it just doesn't work out, unless there is
another solution that I missed.

Yeah, there's no solution. Even if you set the soy value equal to 3%,
there is no value that satisfies all three variables. However, this
solution comes close: x=.336, y=.413, z=.3 (as given). This will allow
60% moisture, 25% fat, and 38% protein. There are other solutions that
could come close, but this should be sufficient.

Oh, I realized the problem! You didn't give me the constitution of the
sausage itself. So with that, I'd have 4 variables and 4 equations,
which would most likely give a good answer.

The question is a vegetarian version of this:

http://webhome.crk.umn.edu/~crobbert/Engineering/ch2_7.asp