What substitution means
What substitution means

A variable is a letter that stands for a number. Substitution means replacing the letter with its given value, then working out the result.
Step-by-step lessons on Edexcel IGCSE Maths Substitution. Each one builds up to exam-style questions. Build confidence with the shared Foundation-tier content first, since roughly 40% of Higher-tier marks are targeted at the grades 4–5 boundary that both tiers have in common.