a)
[tex] \frac{x}{9} = \frac{2}{5} \\ 5 \times x = 9 \times 2 \\ 5x = 18 \\ x = \frac{18}{5} = 3 \frac{3}{5} = 3.6[/tex]
b)
[tex] \frac{x + 1}{4} = \frac{x}{5} \\ 5(x + 1) = 4 \times x \\ 5x+ 5 = 4x \\ x = - 5[/tex]
