A car travels 150 km in 7 hours. What is its average speed?

The average speed is 21.428571 km/h.

v = \frac{d}{t} = \frac{150}{7} = 21.428571\ \text{km/h}

How to work it out

1
Write down what you know: distance d = 150 km, time t = 7 hours. You are asked for the speed v.
2
Use the formula speed = distance ÷ time:
$v = \frac{d}{t} = \frac{150}{7} = \frac{150}{7} = 21.428571$
3
Answer with the unit: 21.428571 km/h.
4
The same formula rearranged: distance = speed × time (21.428571 × 7 = 150 km) and time = distance ÷ speed (150 ÷ 21.428571 = 7 hours).

LaTeX source of the formulas on this page

\[ v = \frac{d}{t} = \frac{150}{7} = 21.428571\ \text{km/h} \]
\[ v = \frac{d}{t} = \frac{150}{7} = \frac{150}{7} = 21.428571 \]

What is the speed if a car travels 150 km in 7 hours?

The average speed is 21.428571 km/h.

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

64.285714 km.