Practice Variable as Placeholder in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A variable acts as a placeholder — a letter or symbol (like x, n, or y) that stands in for an unknown or changing number in a mathematical expression or equation. It represents one specific unknown value that satisfies a given condition.

Like a blank in a sentence: '\_ + 3 = 7' asks 'what number fits here?'

Example 1

easy
In the equation x + 8 = 15, what specific value does x represent?

Example 2

medium
A rectangle has area 24 cm² and width 4 cm. Use a variable to find the length.

Example 3

medium
Maria has some stickers. After giving away 8, she has 15 left. Write an equation and find how many she started with.

Example 4

easy
Find the value of n in 3n = 21.

Example 5

medium
I think of a number, double it, and add 5 to get 19. What is my number?
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