3/20-3/28

The expression \( \frac{3}{20} - \frac{3}{28} \) can be solved by finding a common denominator. The least common multiple (LCM) of 20 and 28 is 140.

Now, we convert each fraction:

1. Convert \( \frac{3}{20} \) to a fraction with a denominator of 140: \[ \frac{3}{20} = \frac{3 \times 7}{20 \times 7} = \frac{21}{140} \]

2. Convert \( \frac{3}{28} \) to a fraction with a denominator of 140: \[ \frac{3}{28} = \frac{3 \times 5}{28 \times 5} = \frac{15}{140} \]

Now we can subtract the two fractions: \[ \frac{21}{140} - \frac{15}{140} = \frac{21 - 15}{140} = \frac{6}{140} \]

Finally, we can simplify \( \frac{6}{140} \): \[ \frac{6}{140} = \frac{3}{70} \]

So, \( \frac{3}{20} - \frac{3}{28} = \frac{3}{70} \).