A car travels 40 km in 6 hours. What is its average speed?

The average speed is 6.6666667 km/h.

v = \frac{d}{t} = \frac{40}{6} = 6.6666667\ \text{km/h}

How to work it out

1
Write down what you know: distance d = 40 km, time t = 6 hours. You are asked for the speed v.
2
Use the formula speed = distance ÷ time:
$v = \frac{d}{t} = \frac{40}{6} = \frac{20}{3} = 6.6666667$
3
Answer with the unit: 6.6666667 km/h.
4
The same formula rearranged: distance = speed × time (6.6666667 × 6 = 40 km) and time = distance ÷ speed (40 ÷ 6.6666667 = 6 hours).

LaTeX source of the formulas on this page

\[ v = \frac{d}{t} = \frac{40}{6} = 6.6666667\ \text{km/h} \]
\[ v = \frac{d}{t} = \frac{40}{6} = \frac{20}{3} = 6.6666667 \]

What is the speed if a car travels 40 km in 6 hours?

The average speed is 6.6666667 km/h.

How far does it go in 3 hours at that speed?

20 km.