Let the total age \(=y\)
\begin{aligned}
&\frac{y}{x}=170 \text { months ( } 14 \text { years }+2 \text { months) } \\
&\Rightarrow y=170 x \text { - (1) } \\
&\text { From the second statement, } \\
&\text { If a pupil of } 15 y \text { ys } 2 \text { months (i.e. } 182 \text { months) joins the } \\
&\text { class and the average age is increased by } 1 \text { month (i.e. } \\
&\text { now } 171 \text { months) then } \\
&\frac{y+182}{x+1}=171 \text { months } \\
&\text { substitute } y=170 x \text { in } \\
&\frac{170 x+182}{x+1}=171 . \\
&171 x+171=170 x+182 \\
&x=182-171=11
\end{aligned}