To tackle this question, you will need to know about the rules for logarithms. Here we are going to use the product rule, where the addition of these two natural logarithms equals the product of the two compnents of each logarithm. In this case, ln(x)+ln(3)=ln(3x).
You are left with the equation ln(3x)=ln(6). To solve this, you use each exponential as a power of the exponontial function. So the equation becomes eln(3x)=eln(6). Since e is the base of the natural logarithm (ln), this equation simplifies to 3x=6, so x=2