To find a fraction equivalent to \( \frac{10}{20} \), you can simplify it by dividing both the numerator and the denominator by their greatest common divisor, which is 10.
\[ \frac{10 \div 10}{20 \div 10} = \frac{1}{2} \]
So, \( \frac{1}{2} \) is an equivalent fraction to \( \frac{10}{20} \). Other equivalent fractions could be \( \frac{2}{4} \), \( \frac{3}{6} \), \( \frac{5}{10} \), etc., as long as both the numerator and denominator are multiplied or divided by the same non-zero number.