The probability of the non-occurrence of an event is `2/7`. Find the probability of the occurrence of the event.

Explanation

To find the probability of the occurrence of an event when the probability of its non-occurrence is given, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the given information**:
We know that the probability of the non-occurrence of an event is \( P(\text{not A}) = \frac{2}{7} \).

2. **Use the relationship between occurrence and non-occurrence**:
The total probability of all possible outcomes must equal 1. Therefore, the probability of the occurrence of the event can be calculated using the formula:
\[ P(\text{A}) = 1 - P(\text{not A}) \]

3. **Substitute the known value**:
Now, substitute the value of \( P(\text{not A}) \) into the formula:
\[ P(\text{A}) = 1 - \frac{2}{7} \]

4. **Perform the subtraction**:
To subtract \( \frac{2}{7} \) from 1, we can express 1 as a fraction with a denominator of 7:
\[ 1 = \frac{7}{7} \]
Therefore,
\[ P(\text{A}) = \frac{7}{7} - \frac{2}{7} = \frac{7 - 2}{7} = \frac{5}{7} \]

5. **Conclusion**:
The probability of the occurrence of the event is:
\[ P(\text{A}) = \frac{5}{7} \]

### Final Answer:
The probability of the occurrence of the event is \( \frac{5}{7} \).