Have you ever known anyone with a stamp collection? Take a look at this dilemma.
To do this, you will need to know how to write single variable equations from verbal models. Pay attention to this Concept and you will learn all that you need to know.
What is the difference between an equation and an expression? Well, an expression is a phrase without an equal sign. This means that the variable in an expression can be changed and the expression can be evaluated differently. An equation has an equal sign. Therefore one side of an equation is equal to a value on the other side.
Now, let's examine how to write equations.
The same key words that helped you write expressions may also help you write equations. Here are some additional key words that you may find helpful.
Key Words for Addition or Multiplication Equations
Key Words for Subtraction Equations
Key Words for Division Equations
how many all together
how many in all
how many total
how many more
how many fewer
how many left
how much change
how many in each
Take a few minutes to write down these key words and phrases in your notebook.
Now let's apply this information.
4 times a number is twelve.
First, notice that we have the word “times” which means to multiply. We also have the word “is” which is a key word for equals.
Seven less than a number is fourteen.
First, notice we have the words “less than” which means subtraction. Then we have the word “is” which is a key word for equals.
Write an equation for each verbal phrase.
Six and a number is twenty.
Eighteen divided by a number is three.
Five times a number is twenty-five.
Here is the original problem once again.
Use a number, an operation sign, a variable, or an equal sign to represent each part of that problem. Since Kelvin has 60 stamps in his collection, represent the number of stamps in Kelvin's collection as 60.
Here are the vocabulary words in this Concept.
a number sentence with variables, numbers and operations.
a letter used to represent an unknown quantity.
a combination of multiple variables, numbers and operations.
a number sentence with an equal sign where the quantity on one side of the equals is the same as the quantity on the other side.
Here is one for you to try on your own.
Use a number, an operation sign, a variable, or an equal sign to represent each part of that problem. Since the question tells us how many liters of lemonade were left after the party, write a subtraction equation.
Here is a video for review.
- This is a Khan Academy video about single variable equation problems. It is a support to this Concept.
Directions: Write an equation for each verbal model.
1. Ten times a number is thirty.
2. Five times a number is fifteen.
3. A number and seven is eleven.
4. A number divided by three is twelve.
5. A number and eighteen is thirty.
6. A number divided by twelve is fourteen.
7. Seven times a number is forty - nine.
8. A number divided by thirteen is seven.
9. Eight times a number is equal to sixty - four.
Directions: Write an algebraic expression for each situation below.
Directions: Write an algebraic equation for each word problem below.