Solution:

Given,

\[\begin{array}{*{35}{l}}

x\text{ }=\text{ }6ab/\text{ }\left( a\text{ }+\text{ }b \right)  \\

\Rightarrow \text{ }x/3a\text{ }=\text{ }2b/\text{ }a\text{ }+\text{ }b  \\

\end{array}\]

applying componendo and dividendo:

\[\begin{array}{*{35}{l}}

~x\text{ }=\text{ }6ab/\text{ }\left( a\text{ }+\text{ }b \right)  \\

\Rightarrow \text{ }x/3b\text{ }=\text{ }2a/\text{ }a\text{ }+\text{ }b  \\

\end{array}\]

applying componendo and dividendo :

From (1) and (2), we get