Final answer:
In order for the given set of ordered pairs to be a function, each x-value must be paired with only one y-value. Since there are no repeated x-values in the given set, any number can replace the missing x-value and still maintain the function property.
Step-by-step explanation:
In order for the set of ordered pairs to be a function, each x-value must be paired with only one y-value. To determine the missing x-value that makes this set a function, we need to check if there are any repeated x-values.
Given the set (2,4), (3,8), (6,2), (x,5), we can see that none of the x-values are repeated. Therefore, any value can replace 'x' and still maintain the function property. Thus, the missing x-value can be any number.