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Example

Solving x63=47\frac{x}{63} = \frac{4}{7}

Solve the proportion x63=47\frac{x}{63} = \frac{4}{7}.

Step 1 — Multiply both sides by the LCD. The denominators are 6363 and 77. Since 63=7963 = 7 \cdot 9, the LCD is 6363. Multiply both sides by 6363:

63x63=634763 \cdot \frac{x}{63} = 63 \cdot \frac{4}{7}

Step 2 — Simplify. On the left, 6363 cancels with the denominator 6363, leaving xx. On the right, 637=9\frac{63}{7} = 9, so the product is 94=369 \cdot 4 = 36:

x=36x = 36

Step 3 — Check. Substitute x=36x = 36 back into the original proportion:

3663=4979=47\frac{36}{63} = \frac{4 \cdot 9}{7 \cdot 9} = \frac{4}{7}

The solution is x=36x = 36. This example illustrates the basic technique for solving a proportion when the variable appears in a numerator: multiply both sides by the LCD to clear fractions, divide out common factors, and verify by substituting the result into the original equation.

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Updated 2026-04-21

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