To calculate how long the supply of chlorine will last, we can divide the total amount of chlorine (150 ounces) by the amount used per application (15/2 ounces) and then multiply by the frequency of application (every 3 days).
150 ounces ÷ (15/2 ounces) × 3 days = 150 ounces ÷ (7.5 ounces) × 3 days = 20 × 3 = 60 days.
Therefore, the supply of chlorine will last for approximately 60 days.