Accepted Answer
x - nominatory - denominator[tex]\frac{3x}{y+12}=\frac{3}{4}\\
\frac{x+7}{3y}=\frac{1}{2}\\\\
3(y+12)=12x\\
2(x+7)=3y\\\\
3y+36=12x\\
2x+14=3y\\\\
2x+14+36=12x\\
10x=50\\
x=5\\\\
3y=2\cdot5+14\\
3y=10+14\\
3y=24\\
y=8\\\\
\frac{x}{y}=\boxed{\frac{5}{8}}[/tex]