Joint, Marginal, and Conditional Distributions

Let the joint probability density function of two continuous random variables \( X \) and \( Y \) be: \[ f_{X,Y}(x, y) = \begin{cases} 4xy, & 0 \leq x \leq 1,\ 0 \leq y \leq 1 \\ 0, & \text{otherwise} \end{cases} \] What is the value of the marginal density \( f_X(0.5) \)?