1) $\dfrac{0,075}{y}.(56x+16y) = 4$
$⇔0,075.(56x+16y) =4y$
$⇔4,2x+1,2y=4y$
$⇔4,2x=2,8y$
$⇔\dfrac{x}{y} = \dfrac{2,8}{4,2} = \dfrac{2}{3}$
2) $\dfrac{0,36.x}{y}.56= 13,44$
$⇔0,36.x.56=13,44y$
$⇔20,16x=13,44y$
$⇔\dfrac{x}{y} = \dfrac{13,44}{20,16} = \dfrac{2}{3}$