Theo bài ra ta có :
\(\frac{x+9}{y+15}=\frac{x}{y}\)
=> y(x + 9) = x(y + 15)
=> xy + 9y = xy + 15x
=> 9y = 15x
=> \(\frac{x}{y}=\frac{9}{15}\)
Vì \(\frac{x}{y}\)tối giản
=> \(\frac{x}{y}=\frac{3}{5}\)
Ta có:
\(\frac{x+9}{y+15}=\frac{x}{y}\)
=> y(x+9)=x(y+15)
<=> xy+9y-xy-15x=0
<=> 9y-15x=0
<=> 3(3y-5x)=0
<=> 3y-5x=0
<=> 3y=5x
<=> \(\frac{x}{y}=\frac{3}{5}\)