Pre-Algebra Examples

$\frac{3}{7} - \frac{4}{m}$

Step 1

To write $\frac{3}{7}$ as a fraction with a common denominator, multiply by $\frac{m}{m}$ .

$\frac{3}{7} \cdot \frac{m}{m} - \frac{4}{m}$

Step 2

To write $- \frac{4}{m}$ as a fraction with a common denominator, multiply by $\frac{7}{7}$ .

$\frac{3}{7} \cdot \frac{m}{m} - \frac{4}{m} \cdot \frac{7}{7}$

Step 3

Write each expression with a common denominator of $7 m$ , by multiplying each by an appropriate factor of $1$ .

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Step 3.1

Multiply $\frac{3}{7}$ by $\frac{m}{m}$ .

$\frac{3 m}{7 m} - \frac{4}{m} \cdot \frac{7}{7}$

Step 3.2

Multiply $\frac{4}{m}$ by $\frac{7}{7}$ .

$\frac{3 m}{7 m} - \frac{4 \cdot 7}{m \cdot 7}$

Step 3.3

Reorder the factors of $m \cdot 7$ .

$\frac{3 m}{7 m} - \frac{4 \cdot 7}{7 m}$

Step 4

Combine the numerators over the common denominator.

$\frac{3 m - 4 \cdot 7}{7 m}$

Step 5

Multiply $- 4$ by $7$ .

$\frac{3 m - 28}{7 m}$