I need to know how to put it together

Question

The owner of a specialty food store wants to mix cashews selling at $8.00/kg and pecans selling at $6.00/kg. How many kilograms of each should be mixed to get 12kg of nuts worth $7.50/kg?

Answer 1

8x + 6(12-x) = 7.5(12)

2x = 90 - 72 = 18

x = 18/2 = 9 kg for cashews

12-9 = 3 kg for pecans

8(9) + 6(3) = 72 +18 = 90 = 7.5(12)

8-7.5 = .5, 7.5-6 = 1.5

the owner needs 1.5/.5 = 3 times as much c as p

9 = 3 times 3 kg