1. **State the problem:** We know that 40 cows eat 40 bags of hush in 450 days. We want to find out how many days it will take for one cow to eat one bag of hush. 2. **Understand the relationship:** The total amount of hush consumed is proportional to the number of cows and the number of days. Since 40 cows eat 40 bags in 450 days, the total hush consumption is 40 bags. 3. **Calculate the total hush consumption in cow-days:** Total cow-days = number of cows $ \times $ number of days = $40 \times 450 = 18000$ cow-days. 4. **Interpretation:** 18000 cow-days correspond to 40 bags of hush. So, one bag of hush corresponds to $\frac{18000}{40} = 450$ cow-days. 5. **Find days for one cow to eat one bag:** Since one bag corresponds to 450 cow-days, and one cow contributes 1 cow-day per day, it will take one cow 450 days to eat one bag of hush. **Final answer:** One cow will eat one bag of hush in **450 days**.