First find the number of adults, then write the fraction in simplest form.<br><br>
&bull; Adults = total passengers - children = 20 - 12 = 8<br>
&bull; Fraction = \(\frac{8}{20}\)<br>
&bull; Simplify: divide numerator and denominator by 4 &rarr; \(\frac{2}{5}\)<br>
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Final Answer: B: \(\frac{2}{5}\)