Răspuns :
[tex]\frac{x}{3}=\frac{y}{4}=k \\\\ x\to 3k \\ y\to 4k \\\\\\ \frac{2x-y}{x+y}\longrightarrow\frac{2*3k-4k}{3k+4k}= \\\\=\frac{6k-4k}{7k}= \\\\=\frac{2 \not k}{7 \not k} \\\\\\ \boxed{\frac{2x-y}{x+y}=\frac{2}{7}}[/tex]
x supra 3=y supra 4
x:3=K rezultă ca x=3K
y:4=K rezultă ca y=4K
2•3K-4K:3K+4K=6K-4K:7K=2K:7K=2 supra 7(simplifici cu K)