the speedometer of a european car gives its speed in kilometres per hour. what is its car speed in miles per hour when speedometer reads 80?

1 km ≈ 0.6214 mi

80 kph * 0.6214 ≈ ? mph

You can look up the conversion factor, which I think is 1.61 km/hr to mph (approximately) which will be 80/1.61= 49.7 mph OR if you don't remember that number just do it from scratch like this using values you do remember.

80 km/hr x 1,000 m/1 km x 100 cm/m x 1 inch/2.54 cm x 1 ft/12 inches x 1 mile/5,280 ft = ? miles/hr.

Not just in Europe, it will be in km/h in every country in the world except

Liberia, Myanmar, and the USA.
Just a little bit if info.

Which leads some to say that the USA is out of step with the world. You've head the joke about "everyone is out of step except my son John".

0.62 ≈ 5/8

so miles/km = 5/8
80 km = 50 mi

A speedometer of a European car is calibrated in kilometers per hour. What is the car's speed in miles per hour when the speedometer reads 50? *

To convert the speed from kilometers per hour to miles per hour, you can use the conversion factor of 0.621371.

To calculate the car's speed in miles per hour when the speedometer reads 80 kilometers per hour, you can use the following equation:

Miles per hour = Kilometers per hour x Conversion factor

Now, substitute the given values:

Miles per hour = 80 km/hr x 0.621371

Calculating this equation:

Miles per hour = 49.70968

So, when the speedometer reads 80 kilometers per hour, the car's speed in miles per hour is approximately 49.71.