Answer: 30° - 3d ≤ 20°
Explanation:
Here the constant rate of decreasing the temperature = d degree,
Thus, the total decreasing in three days = 3d degree,
If the temperature on Monday = 30°
Then the temperature n Thursday = 30° - 3d
Since, The swimming pool is open when the high temperature is higher than 20°
⇒ 30° - 3d ≤ 20°
Which is the required inequality to determine the rate of temperature decrease in degrees Celsius per day, d, from Monday to Thursday.