A dairy farmer wants to mix a 75% protein supplement and a standard 30% protein ration to make 1200 pounds of a high-grade 45% protein ration. How many pounds of each should he use?

Let x be the number of pounds of the 75% protein supplement.

Then, the number of pounds of the 30% protein ration would be 1200 - x.

We can set up the following equation:

0.75x + 0.3(1200 - x) = 0.45(1200)

Simplifying:

0.75x + 360 - 0.3x = 540

0.45x = 180

x = 400

Therefore, the dairy farmer should use 400 pounds of the 75% protein supplement and 800 pounds of the 30% protein ration to make 1200 pounds of a high-grade 45% protein ration.

To determine the number of pounds of each protein supplement the dairy farmer should use, we can set up a system of equations based on the given information.

Let's assume the dairy farmer uses x pounds of the 75% protein supplement and y pounds of the 30% protein ration.

From the given information, we know the following:

1. The total weight of the mixture should be 1200 pounds:
x + y = 1200

2. The desired protein percentage in the mixture should be 45%:
(0.75x + 0.30y) / 1200 = 0.45

Now, we can solve this system of equations to find the values of x and y.

Step 1: Solve the first equation for x:
x = 1200 - y

Step 2: Substitute the value of x in the second equation:
(0.75(1200 - y) + 0.30y) / 1200 = 0.45

Step 3: Simplify the equation:
900 - 0.75y + 0.30y = 0.45 * 1200
900 - 0.75y + 0.30y = 540

Step 4: Combine like terms:
900 - 0.45y = 540

Step 5: Move the constant term to the right side:
-0.45y = 540 - 900
-0.45y = -360

Step 6: Divide both sides by -0.45 to solve for y:
y = -360 / -0.45
y = 800

Step 7: Substitute the value of y into the first equation to solve for x:
x + 800 = 1200
x = 1200 - 800
x = 400

Therefore, the dairy farmer should use 400 pounds of the 75% protein supplement and 800 pounds of the 30% protein ration to make 1200 pounds of a high-grade 45% protein ration.