[tex]9) 7x = 4 | :7\\x = \frac{4}{7} \\10) \frac{1}{7}x = 3|*7\\x = 21\\11) 2x = \frac{4}{13} |:2\\x = \frac{2}{13} \\12) \frac{4}{13} x = \frac{1}{7} | : \frac{4}{13} \\x = \frac{13}{24} \\13) \frac{2}{13} x = 4 | : \frac{2}{13} \\x = 26\\14) \frac{5}{7} x = 20 | : \frac{5}{7} \\x = 24 \\15) -20x = 70|:-20\\x = -3,5[/tex]