Writing Expressions

Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 2 of 51.

Most people write "3 less than a number n" as $3-n$ . That is wrong. Try it with 10: 3 less than 10 is 7, which is $10-3$ . So 3 less than n is $n-3$ . Less than switches the order.

Other words turn into signs directly.

Add: plus, more than, sum.
Subtract: minus, less than, difference.
Multiply: times, twice, product.
Divide: divided by, quotient.

Challenge

Write an expression for: 5 less than twice a number n.

Start the lesson to read it in the interactive player and track your progress.

All lessons in Expressions & Data

1Variables and Expressions

What a Variable IsWriting ExpressionsSubstituting a Value Expressions from Stories Recap: Expressions

4Combining Like Terms

Like Terms Letters and Numbers Negative Terms Two Letters Distribute, Then Collect Recap: Like Terms

7Probability

Chance as a Fraction The Complement Chance as a Percent Expected Count Recap: Probability

10Final Challenges

Final: Two Brackets Final: A Cubic Expression Final: The Phone Plan Final: A Decimal Mean Final: The Last Spin

2Evaluating Expressions

Negative Inputs Powers in Expressions Formulas Recap: Evaluating

5Patterns and Sequences

Continuing a Pattern The Common Difference The nth Term Writing the Rule Recap: Sequences

8Tables and Charts

Reading a Table Totals and Differences Reading a Line Graph Percent of a Total Recap: Tables and Charts

3The Distributive Property

Number Properties Mental Math Distributing Letters Distributing a Minus Recap: Distributing

6Data and Averages

The Mean Mean with Negatives The Median The Mode The Range Recap: Data and Averages

9Perimeter and Area

Perimeter Area of a Rectangle Area of a Triangle Perimeter as an Expression Recap: Perimeter and Area