First find the number of girls, then write the fraction in simplest form.<br><br>
&bull; Girls = total children - boys = 40 - 12 = 28<br>
&bull; Fraction = \(\frac{28}{40}\)<br>
&bull; Simplify: divide numerator and denominator by 4 &rarr; \(\frac{7}{10}\)<br>
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Final Answer: A: \(\frac{7}{10}\)