Here are the steps in solving the value of x in the equation.
1. Subtract 4 on both sides of the equation.
[tex]\begin{gathered} 4+(9\text{ }ln\text{ }x)-4=15.8-4 \\ 9\text{ }ln\text{ }x=11.8 \end{gathered}[/tex]
2. Divide both sides of the equation by 9.
[tex]\frac{9\text{ }ln\text{ }x}{9}=\frac{11.8}{9}\Rightarrow ln\text{ }x=1.31111[/tex]
3. By definition of natural logarithm:
[tex]ln\text{ }x=y\Leftrightarrow e^y=x[/tex]
We can rewrite ln x = 1.3111 as:
[tex]e^{1.31111}=3.71[/tex]
Therefore, the value of x is 3.71. (Option D).
