1)

[tex] - 40 \div ( - 5) = 8 \\ - 48.72 \div 12 = - 4.06 \\ - \frac{26}{63} \div ( - \frac{39}{49} ) = \frac{26 \times 49}{63 \times 39} = \\ \frac{2 \times 7}{9 \times 3} = \frac{14}{27} \\ - 1 \frac{1}{14} \div 5 \frac{5}{7} = - \frac{15 \times 7}{14 \times 40} = \\ - \frac{3}{2 \times 8} = - \frac{3}{16} [/tex]

2)

[tex] - 3.6x = 7.2 \\ x = 7.2 \div ( - 3.6) \\ x = - 2[/tex]

[tex]0.18x = - 0.099 \\ x = - 0.099 \div 0.18 \\ x = - 9.9 \div 18 \\ x = - 0.55[/tex]

[tex] - \frac{5}{9} x = \frac{10}{27} \\ x = \frac{10}{27 } \div ( - \frac{5}{9} ) \\ x = - \frac{10 \times 9}{27 \times 5} \\ x = - \frac{2}{3} [/tex]

3)

[tex]1 \frac{8}{9} \div (1 \frac{3}{4} - 3 \frac{1}{6} ) \times ( - \frac{9}{16} ) = \frac{3}{4} \\ 1) \: \: 1 \frac{3}{4} - 3 \frac{1}{6} = 1 \frac{9}{12} - 3 \frac{2}{12} = \\ 1 \frac{9}{12} - 2 \frac{14}{12} = - 1 \frac{5}{12} \\ 2) \: \: 1 \frac{8}{9} \div ( - 1 \frac{5}{12} ) = \\ - \frac{17 \times 12}{9 \times 17} = - \frac{4}{3} \\ 3) \: \: - \frac{4}{3} \times ( - \frac{9}{16} ) = \\ \frac{4 \times 9}{3 \times 16} = \frac{3}{4} [/tex]