From the question it is given that, \[\mathbf{n}\text{ }\text{ }\mathbf{2},\text{ }\mathbf{4n}\text{ }\text{ }\mathbf{1}\text{ }\mathbf{and}\text{ }\mathbf{5n}\text{ }+\text{ }\mathbf{2}\] are in A.P.
Multiplying by \[2\text{ }to\text{ }4n\text{ }\text{ }1\] then it becomes = \[8n\text{ }\text{ }2\]
So,
\[\begin{array}{*{35}{l}}
8n\text{ }\text{ }2\text{ }=\text{ }n\text{ }\text{ }2\text{ }+\text{ }5n\text{ }+\text{ }2 \\
8n\text{ }\text{ }2\text{ }=\text{ }6n \\
8n\text{ }\text{ }6n\text{ }=\text{ }2 \\
2n\text{ }=\text{ }2 \\
n\text{ }=\text{ }2/2 \\
n\text{ }=\text{ }1 \\
\end{array}\]