Variable $x$ cannot be equal to $0$ since division by zero is not defined. Multiply both sides of the equation by $100x$, the least common multiple of $x,100$.
$$100\times 3000\times 100=x\times 15$$
Multiply $100$ and $3000$ to get $300000$.
$$300000\times 100=x\times 15$$
Multiply $300000$ and $100$ to get $30000000$.
$$30000000=x\times 15$$
Swap sides so that all variable terms are on the left hand side.
