number of girls is \( 9: 7 \). Find the number of boys if the total number of students is 3200 . 19. The sides of a triangle are in the ratio of \( 2: 3: 4 \). If the perimeter is 72 cm , find its sides. 20. In a factory the ratio of number of defective bolts produced to the number of good bulbs is \( 1: 10 \). In one hour the factory produced 330 bolts. Find the number of defective bulbs produced by the

12. \( \frac{6}{\frac{2}{5}}-\frac{\frac{6}{2}}{5} \) Yukanda verilen işlemin sonucu kaçtır? \( \begin{array}{llll}\text { A) } \frac{72}{5} & \text { B) } \frac{-72}{5} & \text { C) } \frac{5}{72} & \text { D) } \frac{-5}{72}\end{array} \)

\( \frac{6}{\frac{2}{5}}-\frac{\frac{6}{5}}{5} \) Yukanda verilen islemin sonucu kaçır? \( \begin{array}{llll}\text { A) } \frac{72}{5} & \text { B) } \frac{-72}{5} & \text { C) } \frac{5}{72} & \text { D) } \frac{-5}{72}\end{array} \)

\( \frac{\frac{5}{3}}{1 \frac{4}{11}} \) Yukarıda verilen işlemin sonucu kaçuır? \begin{tabular}{llll|l} A) \( \frac{11}{9} \) & B) \( \frac{5}{9} \) & C) \( \frac{9}{11} \) & D) \( \frac{9}{5} \)\end{tabular}

احسب: \| 5 \| + \| -2 \|.

Find the 7 th value in the arithmetic sequence described by the explicit formula \( A_{n}=2.5+(n-1) 4 \). (1 point) \( A_{7}=\square \)