Answer:
<u>800 pints</u> of 5% butterfat and <u>200 pints</u> of 20% butterfat is needed.
Step-by-step explanation:
Given:
A dairy wishes to mix together 1,000 pints of milk that contains 8% butterfat.
If the mixture is to be made from milk containing 5% butterfat, and cream
containing 20% butterfat.
Now, to find the pints of each is needed.
Let the pints of 5% butterfat be 
And the pints of 20% butterfat be 
<em>So, the total pints of milk:</em>

......(1)
<em>As, given:</em>
<em>1,000 pints of milk that contains 8% butterfat.</em>
<em>The mixture of milk containing 5% butterfat, and cream containing 20% butterfat.</em>
According to question:


Substituting the value of
from equation (1):



<em>Subtracting both sides by 5000 we get:</em>

<em>Dividing both sides by 15 we get:</em>

<em>The pints of 20% butterfat = 200 pints.</em>
Now, to get the pints of 5% butterfat we put the value of
in equation (1):



<em>The pints of 5% butterfat = 800 pints.</em>
Therefore, 800 pints of 5% butterfat and 200 pints of 20% butterfat is needed.