$n = \frac{v}{{4l}} = 220\,Hz \Rightarrow v = 220 \times 4l$

If $\frac{1}{4}$ of the pipe is filled with water then remaining length of air column is $\frac{{3l}}{4}$

Now fundamental frequency = $\frac{v}{{4\left( {\frac{{3l}}{4}} \right)}} = \frac{v}{{3l}}$ and

First overtone = $3 \times $ fundamental frequency

= $\frac{{3v}}{{3l}} = \frac{v}{l} = \frac{{220 \times 4l}}{l} = 880$$Hz$.