Variable as Placeholder Math Example 1

Follow the full solution, then compare it with the other examples linked below.

Example 1

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

Solution

  1. 1
    Here xx is a placeholder for one specific unknown number.
  2. 2
    Subtract 8 from both sides: x=15−8=7x = 15 - 8 = 7.
  3. 3
    The placeholder xx represents exactly the value 7.

Answer

x=7x = 7
When a variable acts as a placeholder, it stands for one specific unknown value that we need to find. There is exactly one number that makes the equation true.

About Variable as Placeholder

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.

Learn more about Variable as Placeholder →

More Variable as Placeholder Examples

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 s

Example 4 easy

Find the value of [formula] in [formula].

Example 5 medium

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

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