Answer:
<u>19.01 pound</u> of cashews and <u>16.99 pounds</u> of brazil nuts should be used to make a 36 pound mixture that sells for 5.69 per pound.
Step-by-step explanation:
Given:
The nutty professor sells cashews for 7.20 per pound and brazil nuts for 4.00 per pound.
Now, to find each type should be used to make a 36 pound mixture that sells for 5.69 per pound.
Let the quantity of cashews be 
Let the quantity of brazil nuts be 
So, total pound of mixture of nuts:

Now, the total price of mixture per pound:


Substituting the value of
from equation (1) we get:



Subtracting both sides by 144 we get:

Dividing both sides by 3.2 we get:

The quantity of cashews = 19.01 pound.
Now, substituting the value of
in equation (1) we get:

The quantity of brazil nuts = 16.99 pounds.
Therefore, 19.01 pound of cashews and 16.99 pounds of brazil nuts should be used to make a 36 pound mixture that sells for 5.69 per pound.