Answer:
• 85% protein supplement: 480 pounds
,
• 60% protein ration: 720 pounds
Explanation:
Let the number of pounds of 85% protein supplement required = x
The farmer wants to make 1200 pounds (of a high-grade 70% protein ration).
Therefore, the number of pounds of 60% protein ration required = (1200-x) lbs
First, we add the constituents we are mixing together.

The final protein ration we want to obtain:

Equate both:

Then solve the equation for x.

The number of pounds of the 85% protein supplement he should use is 480 pounds.

The number of pounds of the 60% protein ration he should use is 720 pounds.