Introduction:
The question states that M is a number greater than 69 and less than the predecessor of 73. We need to determine how it is not possible for M to be equal to 73.

Understanding the problem:
To solve this problem, we need to understand the given conditions and apply logical reasoning. Let's break down the problem step by step.

Step 1: Identify the predecessor of 73:
To find the predecessor of a number, we subtract 1 from it. Therefore, the predecessor of 73 is 73 - 1 = 72.

Step 2: Identify the range for M:
According to the question, M is a number greater than 69 and less than 72.

Step 3: Analyzing the range:
By analyzing the range, we can conclude that M can be any number between 70 and 71, inclusive. Therefore, M cannot be equal to 73.

Explanation:
The range for M is clearly defined as being greater than 69 and less than the predecessor of 73, which is 72. Therefore, the statement "M is a number greater than 69 and less than 72" rules out the possibility of M being equal to 73. This means that M cannot be 73 according to the given conditions.

Conclusion:
In conclusion, M cannot be equal to 73 because the given conditions specify that M is a number greater than 69 and less than the predecessor of 73, which is 72. By analyzing the range, we can determine that M can be any number between 70 and 71, inclusive.