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How can verbal representations be translated into algebraic expressions and equations?

You may recall that an algebraic expression contains a number, a variable—or a combination of numbers and variables—and at least one arithmetic operation such as addition, subtraction, multiplication, or division. An algebraic equation, on the other hand, makes a statement. It states that two expressions are equal, using an equal sign “ = ”.

Before you can use algebra to solve some of the problems you encounter in daily life (at school, at home, or on the job), you need to be able to translate a verbal representation—the words used to describe a problem into a mathematical expression or equation—one that correctly indicates the mathematical operations involved. The most common operations, of course, are adding, subtracting, multiplying and dividing (+, , ×, ÷).

It’s important to remember that there is more than one way to describe each of the basic operations. Study the table below to review some of the words and phrases that are used to express math equations as verbal representations. When you see or hear these words used to describe a problem, you’ll need to know which operation to include in your equation. (Note that these are just a few examples—you may encounter others from time to time.)

Addition plus, added to, increased by, more than, together
Subtraction decreased by, less than, less, minus, subtracted from, difference, fewer than
Multiplication times, multiplied by, product of
Division divided by, ratio, quotient, per, out of, percent (of 100)
Equals totals, yields, is, equals, gives, will be, was, are

Let’s try translating a word problem into an algebraic equation—so that we can more easily solve it. Read through the problem scenario below.

Lemonade Stand

The cost of setting up a lemonade stand is $50.25. You can sell each cup of lemonade for $0.75. For you to break even, the product of the price of each cup and the number of cups sold must equal the total cost of setting up the lemonade stand.

The slideshow below demonstrates how to translate the verbal representation above into an algebraic equation that correctly represents the situation.

Based on key information in the word problem, you know that it cost $50.25 to set up the lemonade stand. You also know that a cup of lemonade costs $.075. These are the numbers that will appear in your equation.

In the word problem’s third sentence, you encounter the first mathematical keyword: product. A product is what you get when you multiply two things together. According to the word problem, what two things will be multiplied together? What will the product represent?

Next, you’ll need to substitute the numerical values in the word problem into the expression:

price of a cup of lemonade · number of cups sold

Since you know the price you’re charging for each cup of lemonade, you can substitute that value into the expression you just created. You don’t know the number of cups sold, however—that number is an unknown variable. It doesn’t matter what letter you use to represent the variable, but using a letter that is related to the problem often works best. For this problem, use n to represent the number of cups.

\(\mathsf{ $0.75 \cdot n }\) or \(\mathsf{ $0.75n }\)

You don’t have an equation yet, only an expression. If you continue reading the word problem, though, you will see the next mathematical keyword: equal. The word problem’s last sentence tells you that you’ll need to set the expression “price of a cup of lemonade · number of cups sold” to equal “the total cost of setting up the lemonade stand.”

\(\mathsf{ $0.75 \cdot n }\) = cost of setting up the lemonade stand

Since you know the cost, you can substitute that value into the newly formed equation.

\(\mathsf{ $0.75n = $50.25 }\)

Now you have a full algebraic equation that represents the information in the word problem.

Read through the problem scenario below

Woman looking at shoes

Laurie spent $27 on shoes, which was $11 less than twice what she spent on a pair of jeans.

Answer each question, then click the question to check your work.