  # Substitute Numbers for Letters into an Expression

In this worksheet, students must substitute numbers in place of letters to evaluate the given expressions. This content is premium and exclusive to EdPlace subscribers. Key stage:  KS 2

Curriculum topic:   Maths and Numerical Reasoning

Curriculum subtopic:   Equations and Algebra

Difficulty level:   #### Worksheet Overview

In algebra, we use a letter to represent an unknown number.

Sometimes we want to substitute a number for the letter in an expression.

Example 1

Evaluate 2a - b when a = 6 and b = 7.

2a - b means (2 × a) - b

So this is (2 × 6) - 7

i.e.  12 - 7 = 5.

Example 2

Work out the value of 5(x - 2) when x = 9.

Substitute x for 9 to get

5(9 - 2) which means 5 × (9 - 2).

Now work out the brackets first to get 9 - 2 = 7.

So this is 5 × 7 = 35

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