Ответ:\(\frac{x}{5}=8\)\(x=8\cdot5=40\)\(\frac{y}{7}=9\)\(y=9\cdot7=63\)\(\frac{3x}{4}=12\)\(3x=48\)\(x=16\)\(\frac{5y}{6}=15\)\(5y=90\)\(y=18\)Ответ: x = 40; y = 63; x = 16; y = 18.