If x : y = 3 : 4, then the value of 5x - 2y7x + 2y = ?

Answer: Option C

$$\begin{array}{rl}& x:y=3:4\\ & \therefore \frac{5x-2y}{7x+2y}\\ & =\frac{5\times 3-2\times 4}{7\times 3+2\times 4}\\ & =\frac{15-8}{21+8}\\ & =\frac{7}{29}\end{array}$$