Answer:
12
Step-by-step explanation:
Let K = pounds of Kenyan-French roast
S = pounds of Sumatran
So 8K + 12S = 10*24 for the total cost.
K + S = 24 for the total weight.
S = 24 - K, so 8K + 12(24 - K) = 240.
8K + 288 - 12K = 240 or 4K = 48 or K = 12. So, S = 12.
We would need 12 pounds each to make a blend that would cost $10 per pound.