Explicație pas cu pas:

[tex] \dfrac{7x}{3y} = \dfrac{4}{3} \iff \dfrac{x}{y} = \dfrac{3 \cdot 4}{7 \cdot 3} \\ \implies \dfrac{x}{y} = \dfrac{4}{7}[/tex]

a)

[tex]\dfrac{2y - x}{x} = \dfrac{2y}{x} - \dfrac{x}{x} = 2 \cdot \dfrac{y}{x} - 1 = 2 \cdot \dfrac{7}{4} - 1 = \dfrac{14 - 4}{4} = \dfrac{10}{4} = \bf \dfrac{5}{2}[/tex]

b)

[tex]\dfrac{2y - x}{y} = \dfrac{2y}{y} - \dfrac{x}{y} = 2 - \dfrac{4}{7} = \dfrac{14 - 4}{7} =\bf \dfrac{10}{7}[/tex]

c)

[tex]\dfrac{4x - y}{y} = \dfrac{4x}{y} - \dfrac{y}{y} = 4 \cdot \dfrac{x}{y} - 1 = 4 \cdot \dfrac{4}{7} - 1 = \dfrac{16 - 7}{7} =\bf \dfrac{9}{7}[/tex]