Question

which expression uses a common denominator to rewrite $\frac{1}{3} - \frac{1}{9}$? $\frac{3}{9} - \frac{1}{9}$ $\frac{3}{3} - \frac{1}{3}$ $\frac{9}{1} - \frac{3}{1}$ $\frac{9}{9} - \frac{1}{9}$

Explanation:

Step1: Find common denominator

The least common denominator of 3 and 9 is 9.

Step2: Rewrite first fraction

Multiply numerator and denominator of $\frac{1}{3}$ by 3: $\frac{1 \times 3}{3 \times 3} = \frac{3}{9}$

Step3: Keep second fraction unchanged

$\frac{1}{9}$ already has denominator 9, so it stays $\frac{1}{9}$

Step4: Rewrite the expression

Substitute the rewritten fractions into the original subtraction: $\frac{3}{9} - \frac{1}{9}$

Answer:

$\frac{3}{9} - \frac{1}{9}$