[tex]5 \times \frac{1}{5} = 1[/tex]

[tex] \frac{2}{3} x - \frac{1}{18} x + \frac{1}{2} x = 2 \frac{2}{9} \\ \frac{12}{18} x - \frac{1}{18} x + \frac{9}{18} x = 2 \frac{2}{9} \\ \frac{21}{18} x - \frac{1}{18} x = 2 \frac{2}{9} \\ \frac{20}{18} x = 2 \frac{2}{9} \\ \frac{10}{9} x = 2 \frac{2}{9} \\ x = 2 \frac{2}{9} \div \frac{10}{9} \\ x = \frac{20 \times 9}{9 \times 10} \\ x = 2[/tex]

[tex] - 8b - (4b - 3a) = - 8b - 4b + 3a = \\ - 12b + 3a = 3(a - 4b) = 3 \times ( - 5) = - 15[/tex]