Advanced Math Concepts

Three-Part Ratios (A : B : C)

Three-part ratios describe proportional relationships across three interdependent components simultaneously.

How to Simplify a Three-Part Ratio

To reduce a three-part ratio (such as 18 : 24 : 30), you must find a common divisor that divides into all three terms without a remainder:

  1. Find GCD of first two numbers: GCD(18, 24) = 6.
  2. Find GCD of that result and the third number: GCD(6, 30) = 6.
  3. The overall 3-way GCD is 6.
  4. Divide every term by 6: 18 ÷ 6 = 3, 24 ÷ 6 = 4, and 30 ÷ 6 = 5.
  5. The simplified ratio is 3 : 4 : 5.

How to Divide a Total Amount into Three Parts

Suppose an inheritance of $60,000 is split among three siblings in the ratio 2 : 3 : 5:

  1. Sum the parts: 2 + 3 + 5 = 10 total parts.
  2. Calculate single part value: $60,000 ÷ 10 = $6,000 per part.
  3. Allocate shares:
    • Sibling 1 (2 parts): 2 × $6,000 = $12,000 (20%)
    • Sibling 2 (3 parts): 3 × $6,000 = $18,000 (30%)
    • Sibling 3 (5 parts): 5 × $6,000 = $30,000 (50%)
  4. Check: $12,000 + $18,000 + $30,000 = $60,000.
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Reviewed for accuracy: October 2026 by Ratio Calculator Mathematical Review Team • Topic: Three-Way Ratio Mathematics