Let:
x = Pounds of walnuts in the mix.
Each pound of walnuts costs $0.80. thus x pounds of walnuts cost 0.8x dollars.
Each pound of cashews costs $1.25 and the mix will contain 8 pounds of cashews, so the cost is 8*$1.25 = $10
The total cost of the mix is, therefore: 0.8x + 10 dollars.
We are also given the pound of mix costs $1.00 and we have a total of 8 + x pounds, so the total cost of the mix is 1*(8 + x) dollars.
Equating both costs:
0.8x + 10 = 1*(8 + x)
Operating:
0.8x + 10 = 8 + x
Subtracting x and 10:
0.8x - x = 8 - 10
Simplifying:
-0.2x = -2
Dividing by -0.2:
x = -2/(-0.2)
x = 10
Answer: 10 pounds