Soybean meal is 18% protein and cornmeal is 9% cornmeal, how much of each mixed together will you use to make a 360lb mixture that is 17% protein.
I think you mean "cornmeal is 9% protein". Let x be the amount (in lb.) of soybean meal. Then 360 - x is the number of pounds of corn meal.
0.17 * 360 = 0.18 x + 0.09 (180 -x)
That is s mathematical statement that 17% of the mixture is protein.
Solve it for x
61.2 = 0.18x + 16.2 - 0.09x
45 = 0.09 x