[wabidon]

soy protein mix is 18% and corn meal mix is 9% a bag of meal weighs 360lbs and needs 10% protein how much soy and how much cornmeal will there be ?

I figured 24 lbs of soy and 12lbs of cornmeal to = 36 lbs of protein that is ten percent of protein in mix ?

[ArcSine]

Let S be the number of pounds of soy mix, and C represent the pounds of corn mix.

Now you set up two equations: To make up a bag of meal we need 360 pounds total:

S + C = 360

We also need that bag o' meal to contain 36 lbs of protein:

0.18S + 0.09C = 36

Now just use your favorite tactic--either elimination or substitution.