To cross-multiply the equation \(30x = \) something (you didn't specify the other side of the equation), we typically need to have a fraction on the right side.
For example, if the equation were:
\[ 30x = \frac{a}{b} \]
To cross-multiply, you would multiply \(30x\) by \(b\) and multiply \(a\) by \(1\) (the implicit denominator of \(30x\)):
\[ 30x \cdot b = a \cdot 1 \]
which simplifies to:
\[ 30bx = a \]
If you provide the full equation, I can give you a more specific answer!