Given: \(x : y = 3 : 4\) Let \(x = 3p\) and \(y = 4p\) [Where \(p\) is a real number and \(p \ne 0\)] ∴ \((3y - x) : (2x + y) = \frac{3y - x}{2x + y}\) = \(\frac{3 \times 4p - 3p}{2 \times 3p + 4p}\) = \(\frac{12p - 3p}{6p + 4p}\) = \(\frac{9p}{10p}\) = \(\frac{9}{10}\) ∴ \((3y - x) : (2x + y) = 9 : 10\) (Answer)