A car travels 90 miles in 2 hours. What is its average speed?

The average speed is 45 mph.

v = \frac{d}{t} = \frac{90}{2} = 45\ \text{mph}

How to work it out

1
Write down what you know: distance d = 90 miles, time t = 2 hours. You are asked for the speed v.
2
Use the formula speed = distance ÷ time:
$v = \frac{d}{t} = \frac{90}{2} = 45$
3
Answer with the unit: 45 mph.
4
The same formula rearranged: distance = speed × time (45 × 2 = 90 miles) and time = distance ÷ speed (90 ÷ 45 = 2 hours).

LaTeX source of the formulas on this page

\[ v = \frac{d}{t} = \frac{90}{2} = 45\ \text{mph} \]
\[ v = \frac{d}{t} = \frac{90}{2} = 45 \]

What is the speed if a car travels 90 miles in 2 hours?

The average speed is 45 mph.

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

135 miles.