The swimming pool is open when the high temperature is higher than 20 C. Lainey tried to swim on Monday and Thursday (which was 3 days later). The pool was open on Monday, but it was closed on Thursday. The high temperature was 30 C on Monday, but decreased at a constant rate in the next 3 days. Write an inequality to determine the rate of temperature decrease in degrees Celsius per day, d, from Monday to Thursday.

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Given Information: Let's denote the rate of temperature decrease in degrees Celsius per day as d. Since the temperature was 30 C on Monday and the pool was open, we know that the temperature was higher than 20 C on that day. By Thursday, the temperature had decreased enough for the pool to be closed, which means the temperature was 20 C or lower.Equation Setup: We can set up an equation to represent the temperature on Thursday. The temperature on Thursday would be the temperature on Monday minus the rate of decrease times the number of days that have passed, which is 3 days. Temperature on Thursday = Temperature on Monday - (d * 3 days)Substitution: We know the temperature on Monday was 30 C, so we can substitute that value into our equation. Temperature on Thursday = 30 C - (d * 3 days)Inequality Representation: Since the pool was closed on Thursday, the high temperature must have been 20 C or lower. Therefore, we can write an inequality to represent this situation. 20 C ≥ 30 C - (d * 3 days)Isolating Variable: Now, we need to solve for d to find the rate of temperature decrease per day. We can do this by isolating d on one side of the inequality. 20 C ≥ 30 C - 3dSubtraction Step: Subtract 30 C from both sides of the inequality to get: -10 C ≥ -3dDivision Step: Divide both sides by -3 to solve for d. Remember that dividing by a negative number will reverse the inequality sign. (-10 C) / (-3) ≤ dFinal Solution: Solving the division gives us: 10/3 C/day ≤ d or approximately 3.33 C/day ≤ d

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