Example

Example of Contrasting Subtraction and Multiplication of 5x6\frac{5x}{6} and 310\frac{3}{10}

This example contrasts the procedures for subtracting and multiplying the fractions 5x6\frac{5x}{6} and 310\frac{3}{10}. Identifying the operation determines if a common denominator is necessary.

ⓐ Subtracting 5x6310\frac{5x}{6} - \frac{3}{10}: Subtraction requires a least common denominator (LCD). The LCD for 66 and 1010 is 3030. First, rewrite each fraction as an equivalent fraction with the LCD: 5x565=25x30\frac{5x \cdot 5}{6 \cdot 5} = \frac{25x}{30} and 33103=930\frac{3 \cdot 3}{10 \cdot 3} = \frac{9}{30}. Next, subtract the numerators and place the difference over the common denominator: 25x930\frac{25x - 9}{30}. There are no common factors between the numerator and denominator, so the expression is simplified.

ⓑ Multiplying 5x6310\frac{5x}{6} \cdot \frac{3}{10}: Multiplication does not require a common denominator. Multiply the numerators and denominators directly: 5x3610=15x60\frac{5x \cdot 3}{6 \cdot 10} = \frac{15x}{60}. Rewrite to reveal common factors: 5x32325\frac{5x \cdot 3}{2 \cdot 3 \cdot 2 \cdot 5}. Removing the common factors of 33 and 55 from both the numerator and denominator simplifies the expression to x4\frac{x}{4}.

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Updated 2026-05-02

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