A rate is a special kind of ratio that compares quantities, or amounts, with different units. This means the two quantities in a rate measure different things. One of the quantities often measures something like time, distance or money. A rate shows how much of something is happening per unit of another thing. For example, one rate you see very often is miles per hour. That rate tells you how many miles you’re going for every hour you travel. If you’re driving 35 miles per hour, you travel 35 miles every hour.

Which of the following can be written as a rate?

A word we often use when we talk about rates is “per.” Per means “for each” or “for every.” So when you see a phrase like “100 calories per hour” or “3 dollars per gallon,” it means the same as “100 calories for every hour” or “3 dollars for every gallon.”

What is another way of saying that Janelle can ride her bike at a rate of 15 kilometers per hour?

If Kiara earns $15 per hour for babysitting, how many hours will it take her to earn $90?