GCSE & IGCSE maths practice

Substitution questions and answers

Substitution means replacing each letter with its value and working out the answer. Put negative numbers in brackets so the signs come out right: if $x = -3$ , then $x^2 = (-3)^2 = 9$ . Then follow the order of operations (BIDMAS).

8 questions · Foundation tier · Every answer is checked as you type it, with a full worked solution. Updated 27 Oct 2026.

Start the questions Order of operations: lesson

Where substitution comes up

GCSE (AQA, Edexcel, OCR)	Foundation and Higher: substitute numerical values into formulae and expressions, including scientific formulae.
Cambridge IGCSE (0580)	Core and Extended: substitute numbers into expressions and formulas.

The method

Write the expression out with each letter replaced by its value in brackets.
Work out powers first, then multiplication and division, then addition and subtraction.
Take care with negatives: (−3)² = 9 but −3² = −9.

Substitution questions

Try each one before looking at the hint. If you're stuck, the AI tutor can talk you through it step by step.

Warm-up

Question 1Warm-upFoundation

Work out $2a + b$ when $a = 3$ and $b = 5$ .

Question 2Warm-upFoundation

Work out $x^2 + 3x$ when $x = -2$ .

Exam-style

Question 3Exam-styleFoundation

$v = u + at$ . Find $v$ when $u = 5$ , $a = 3$ and $t = 4$ .

Question 4Exam-styleFoundation

Work out $3p - 2q$ when $p = 4$ and $q = -3$ .

Question 5Exam-styleFoundation

$E = \tfrac{1}{2}mv^2$ . Find $E$ when $m = 4$ and $v = 6$ .

Question 6Exam-styleFoundation

Work out $2x^2 - 5x$ when $x = -3$ .

Challenge

Question 7ChallengeFoundation

$F = \dfrac{9C}{5} + 32$ . Find $F$ when $C = 25$ .

Question 8ChallengeFoundation

$s = ut + \tfrac{1}{2}at^2$ . Find $s$ when $u = 3$ , $t = 4$ and $a = -2$ .

Common mistakes

Writing 2x as 2 followed by the digit (x = 5 gives 10, not 25).
Squaring a negative and getting a negative.
Ignoring the order of operations.

Stuck on one of these?

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Sources

The questions are our own. The “where it comes up” notes are from each board's published specification, checked on 26 October 2026:

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