Final answer:
Without the exact expression, it is impossible to determine the value for a = 5 and k = -2. Hypothetically, for an expression like a + k, the answer would be 3, but this is not necessarily related to the student's incomplete question.
Step-by-step explanation:
The student's question appears to be incomplete and thus cannot be specifically answered as the expression is not provided. Due to the lack of necessary information, such as the exact expression to evaluate, it is impossible to determine the value of the expression when a = 5 and k = -2.
If, for example, the expression was a + k, substituting a = 5 and k = -2 would result in an answer of 3. Nonetheless, since we lack full context, this is merely a hypothetical scenario and not the definitive answer to the incomplete question.
Generally, to substitute values into an expression, simply replace the variables with the provided numbers and perform the indicated operations to find the result.