<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation
Our Terms of Use (click here to view) have changed. By continuing to use this site, you are agreeing to our new Terms of Use.

Single Variable Expressions

Use symbols and operations to understand and define variables.

Atoms Practice
Estimated12 minsto complete
Practice Single Variable Expressions
This indicates how strong in your memory this concept is
Estimated12 minsto complete
Practice Now
Turn In
Dog Diets

Do you have a pet dog, or have you ever wanted one? Feeding your canine companion is obviously an important thing to consider. But what if you didn’t know how many calories to feed the dog and only knew the dog’s weight? Could you use an expression to figure how many calories the dog should eat? What values would you need to know?

Why It Matters

Veterinarians have figured out a simple way to calculate how many calories are needed to feed dogs of different weights and sizes. If you take the weight of your dog in kilograms, multiply it by 30, and add 70, you can get your dog’s resting energy requirement (RER) in calories:

\begin{align*}30(\text{dog's weight})+70=\text{RER}\end{align*}

Notice that you have a variable expression to evaluate; you only need to know the dog’s weight in order to calculate the number of calories needed. Medium-sized dogs like the Boxer above weigh an average of 28 kilograms. How many calories would the RER of such a dog be?

To find out, substitute 28 for the dog’s weight in the expression above:


Thus, a 28-kilogram Boxer would have an RER of 910 calories.

It’s important to note, however, that the RER, or resting energy requirement, does not take the dog’s activity into consideration. You can see how activity level factors into canine diets here: 

Explore More

Check out the following resources to learn more about the care and feeding of dogs.




Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes
Please to create your own Highlights / Notes
Show More

Image Attributions

Explore More

Sign in to explore more, including practice questions and solutions for Single Variable Expressions.
Please wait...
Please wait...