We are given the equation:
\[
\frac{X \ Y}{- X \times Y} = \frac{3}{8}.
\]
Step 1: Solve for \( X \ Y \)
Using the definition of the operation \( \ \), we know:
\[
X \ Y = X + Y \quad \text{(if both \( X \) and \( Y \) are positive)}.
\]
Substitute this into the equation:
\[
\frac{X + Y}{- X \times Y} = \frac{3}{8}.
\]
Step 2: Simplify the equation
Now multiply both sides by \( - X \times Y \):
\[
X + Y = \frac{3}{8} \times (- X \times Y).
\]
\[
X + Y = - \frac{3}{8} X \times Y.
\]
Step 3: Analyze the equation
We need to find conditions for \( X \) and \( Y \) that satisfy this equation.
For the equation to hold, we analyze the signs of \( X \) and \( Y \).
- If \( X > 0 \) and \( Y < 0 \), the product \( - X \times Y \) will be positive, making the equation valid.
- Other combinations of signs for \( X \) and \( Y \) will not satisfy this equation.
Thus, the correct answer is that \( X > 0 \) and \( Y < 0 \).