Namita travels 20 km 50 m every day. Out of this she travels 10 km 200 m by bus and the rest by auto. How much distance does she travel by auto?

Total distance travelled = 20 km 50 m

= 20 km + $\dfrac{50}{1000}$ km = 20 km + 0.050 km = 20.050 km

Distance travelled by bus = 10 km 200 m

= 10 km + $\dfrac{200}{1000}$ km = 10 km + 0.200 km = 10.200 km

Distance travelled by auto = 20.050 - 10.200

Writing in column form and subtracting:

$\begin{array}{r} \phantom{+}20.050 \ -\space 10.200 \ \hline 9.850 \end{array}$

Hence, Namita travels 9.850 km or 9 km 850 m by auto.