Solution-
Let the C.P. $=$ Rs. 100
$
\begin{aligned}
\therefore \text { S.P. } &=100+10 \% \text { of } 100 \\
&=100+10=\text { Rs. } 110
\end{aligned}
$
$\because$ When the C.P. is Rs. 100 , then the S.P. = Rs. 110
$\therefore \quad$ When the C.P. is Re. 1 , then the
$
\text { S.P. }=\text { Rs. } \frac{110}{100}
$
$\therefore$ When the C.P. is Rs. 20 , then
$
\text { the S.P. }=\text { Rs. } \frac{110}{100} \times 20
$
$
\text { = Rs. } 22 \text {; Ans. }
$