In the context of a mathematical statement involving percentages, the percentage is typically represented by a number out of a total.
The number 50 represents a part, while 100 often represents the whole. In this case, if you're trying to determine the percentage represented by 50 in relation to 100, you would calculate it as follows:
\[ \text{Percentage} = \left( \frac{50}{100} \right) \times 100 = 50% \]
So, if the question mark (?) is meant to represent a percentage, it would be 50% in this context.