This study notes covers Worked Example 4: Basic Substitution within Simplifying Expressions for GCSE Mathematics. Revise Simplifying Expressions in Algebra for GCSE Mathematics with 11 exam-style questions and 5 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 11 of 19 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Worked Example 4: Basic Substitution
Find the value of 3a + 2b when a = 4 and b = 5
Step 1 Write the expression
3a + 2b
Step 2 Substitute the values
= 3(4) + 2(5)
Replace a with 4 and b with 5
Step 3 Calculate using BIDMAS
= 12 + 10
= 22
Practice questions for Simplifying Expressions
Which two terms are like terms?
Explain why 3x + 2x² cannot be simplified to 5x³.
Quick recall flashcards
Like Terms
Terms with same letter and power: 2x and 5x are like terms
Substitution
Replace each letter with its given value, then calculate