First we get 30% ounces of peanuts in mixed nuts: (0.3) * (32) = 9.6 To find the percentage of peanut concentration of the final mix if you add x ounces of peanuts: % of peanuts = ((x + 9.6) / (x + 32)) * (100) Answer: An expression can be used is: % of peanuts = ((x + 9.6) / (x + 32)) * (100)