Cost of Hazelnuts per pound = $6.50
Cost of cashews per pound = $4.50
Total quantity to buy C + H = 60 pounds of mixture
Cost of the Mixture per pound = $5.10
6.5H + 4.5C = 60 x 5.10 => 1.3H + 0.9C = 61.2 => 13H + 9C = 612
We have C + H = 60 => H = 60 - C
13(60 - C) + 9C = 612 => 780 - 13C + 9C = 612 => 4C = 780 - 612
=> C = 42, then H = 60 - 42 = 18
So the mixture will be 42 pounds of cashews and 18 pounds of Hazelnuts.