Menu

Substituting a Value

Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 3 of 51.

Find $2n+5$ when n is 7. Put 7 in place of n, in brackets: $2 \cdot \left(7\right) + 5$ . Multiply first: $14+5$ is 19.

Putting a number in place of a letter is called substituting. The brackets remind you to multiply. 2n is 2 times 7, not 27.

Challenge

Find the value v of $3n+4$ when n is 13. Write v equal to the expression with 13 in place of n, then work it out.

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 Is Writing ExpressionsSubstituting a ValueExpressions 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