Question

Puja started from home and walked 20 km towards the east and then she took a left and walked 10 km. She walked another 10 m after taking a left turn and then walked 15 km and reached back home. The total distance covered by Puja is ___ km.

Answer 1

From the figure above (not drawn to scale)
The total distance covered by Puja = AB + BC + CD + DA
= 20 km + 10 km + 10 m + 15 km

Adding or subtracting quantities with units is allowed only if the quantities have the same units.
Here to get the total distance in km, we should convert the distance given in meters to kilometers.

$\because$ 1 m = $\frac{1}{1000}$ km
$\therefore$ 10 m = $\frac{10}{1000}$ km = 0.01 km

Therefore, total distance covered by Puja = 20 + 10 + 0.01 + 15 = 45.01 km