Verified answer

а)

[tex] \frac{x}{15} = \frac{2}{5} \\ 5x = 2 \times 15 \\ 5x = 30 \\ x = 30 \div 5 \\ x = 6[/tex]

б)

[tex] \frac{2}{9} = \frac{x}{18} \\ 9x = 2 \times 18 \\ 9x = 36 \\ x = 36 \div 9 \\ x = 4[/tex]

в)

[tex] \frac{0.8}{x} = \frac{4}{70} \\ 4x = 0.8 \times 70 \\ 4x = 56 \\ x = 56 \div 4 \\ x = 14[/tex]

г)

[tex] \frac{5.4}{0.9} = \frac{y}{5} \\ 0.9y = 5 \times 5.4 \\ 0.9y = 27 \\ y = 27 \div 0.9 \\ y = 30[/tex]