⚖️ ALGEBRA & RATIO TOOL

Proportion Calculator 2026 - Solve Proportion Equations A/B = C/D

Solve equal ratio and proportion equations instantly using cross multiplication for any unknown variable X.

Figure 1: Cross multiplication proportion solving model.

📋 Table of Contents

1. Interactive Proportion Calculator Tool
2. Understanding Direct & Inverse Proportions
3. Cross Multiplication Formula
4. Step-by-Step Worked Example
5. Frequently Asked Questions (FAQ)

⚡ Interactive Proportion Solver (A / B = C / D)

Leave ONE box blank or type 'X' in the unknown variable field:

=

Solved Proportion Value:

X = 0

2. Understanding Direct & Inverse Proportions

A proportion is an equation stating that two ratios are equal. Proportions are widely used in recipe scaling, architectural blueprints, map scales, currency exchange rates, and physics equations.

3. Cross Multiplication Formula

Equation: A / B = C / D
Cross Product: A × D = B × C

Solving for unknown D: D = (B × C) / A
  

4. Step-by-Step Worked Example

Suppose 5 items cost $20. How much will 25 items cost?

Ratio 1 (Known)	Ratio 2 (Unknown)	Cross Multiply Solution
5 items / $20	25 items / $X	5 × X = 20 × 25
Result	5X = 500	X = $100.00

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between a ratio and a proportion?

Answer: A ratio compares two quantities (e.g. 2:3), whereas a proportion states that two ratios are equal (e.g. 2:3 = 4:6).

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