X/3 : 287x

To simplify the expression \( \frac{x}{3} : 287x \), you can rewrite the division as a fraction:

\[ \frac{\frac{x}{3}}{287x} \]

This can be simplified by multiplying the numerator by the reciprocal of the denominator:

\[ \frac{x}{3} \cdot \frac{1}{287x} = \frac{x}{3 \cdot 287x} \]

Now, since \( x \) is in both the numerator and the denominator, you can cancel \( x \) (assuming \( x \neq 0 \)):

\[ = \frac{1}{3 \cdot 287} \]

This further simplifies to:

\[ = \frac{1}{861} \]

So the simplified form of \( \frac{x}{3} : 287x \) is:

\[ \frac{1}{861} \]