10 pounds of walnuts cost $50. how much does 1 pound of walnuts cost? find the constant of proportionality. question 5 options: 50/10 = 5. one pound of walnuts costs $5. the constant of proportionality is 5. 10/50 = .2. one pound of walnuts costs $0.20. the constant of proportionality is 0.2. 10 * 50 = 500. one pound of walnuts costs $500. the constant or proportionality is 500. 10 * 1 = 10. one pound of walnuts costs $10. the constant or proportionality is 10.