Let's call X the number of pounds of cashews and Y the number of pounds of Brazil nuts.
Now, we want to make 33 pounds of the mixture, so:
X + Y = 33
Adittionally, every pound mixture will be sell for $5.64 per pound. It means that:
7X + 4Y = 5.64*33
7X + 4Y = 186.12
Because every pound of cashews cost $7 and every pound of Brazil nuts cost $4
Then, we can solve for X on the first equation and replace it on the second as:
So, we can solve for Y as:
Now, we can calculate X as:
Therefore, we need to use 18.04 pounds of cashews and 14.96 pounds of Brazil nuts to make a 33 pounds mixture that sells for $5.64 per pound
Answer 18.04 pounds of cashews and 14.96 pounds of Brazil nuts