Answer : Option C

Explanation :

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Solution 1
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Let the time in which he travelled on foot = x hr
Then the time in which he travelled on bicycle = (9 - x) hr
distance = speed x time

$MF#%\begin{align}
&\Rightarrow 4x + 9(9 - x) = 61\\
&\Rightarrow 4x + 81 - 9x = 61\\
&\Rightarrow 5x = 20\\
&\Rightarrow x = 4\\\\\\\\
&\Rightarrow \text{ distance travelled on foot = }4x = 4 \times 4 = 16\text{ km}\\
\end{align} $MF#%

$MF#%\begin{align}
&\text{Time = }\dfrac{\text{Distance}}{\text{Speed}}\\\\
&\Rightarrow \dfrac{x}{4} + \dfrac{(61-x)}{9} = 9\\\\
&\Rightarrow 9x + 4 \times 61 - 4x = 36 \times 9 \\\\
&\Rightarrow 5x + 244 = 324\\\\
&\Rightarrow 5x = 324 - 244 = 80\\\\
&\Rightarrow x = \dfrac{80}{5} = 16\text{ km}\\
\end{align} $MF#%