1. **State the problem:** Solve the expression $2x 9$. It seems like the problem is to multiply $2x$ by $9$. 2. **Apply multiplication:** Multiply the coefficient $2$ by $9$ while keeping the variable $x$ as is. 3. **Calculate:** $$2x \times 9 = (2 \times 9)x = 18x$$ 4. **Final answer:** The simplified expression is $18x$.