[tex] \frac{x}{y} = \frac{5}{7} = > x = \frac{5y}{7} \\ 3 \times \frac{5y}{7} - 2y = 3 \\ 15y - 2y \times 7 = 3 \times 7 \\ 15y - 14y = 21 \\ y = 21 \\ x = \frac{5 \times 21}{7} = 5 \times 3 \\ x = 15 [/tex]
