a. variables:
x: pounds of crude protein supplement
y: pounds of corn
40% of crude protein supplement is protein.
8.6% of corn is protein
14% of the balanced ration is protein
In 100 pounds of ration we get:
0.4x + 0.086y = 0.14*100
0.4x + 0.086y = 14 (eq. 1)
Also
x + y = 100 (eq. 2)
Isolating x from the second equation,
x = 100 - y
Replacing this result into the first equation,
0.4(100 - y) + 0.086y = 14
0.4*100 - 0.4y + 0.086y = 14
40 - 0.314y = 14
-0.314y = 14 - 40
y = (-26)/(-0.314)
y = 82.8
Then
x = 100 - 82.8
x = 17.2
There are 17.2 pounds of crude protein supplement and 82.8 pounds of corn in 100 pounds of ration
b. First, we need to compute how many pounds of each feedstuff is in 1 ton, using the next proportions:
Protein supplement cost $12.50 per 50 pounds, then 344 lb cost: