Răspuns :
[tex]\frac{a}{b}=\frac{6}{7}\Rightarrow \frac{a}{6}=\frac{b}{7}=k\Rightarrow a=6k,b=7k;\\
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\frac{b-a}{b+a}=\frac{7k-6k}{7k+6k}=\frac{1}{13}\\
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\frac{3a-2b}{a+b}=\frac{18k-14k}{6k+7k}=\frac{4}{13}[/tex]
a/b=6/7
b-a/b+a=7-6/7+6=1/13
3a-2b/a+b=3*6-2*7/6+7=18-14/13=4/13
b-a/b+a=7-6/7+6=1/13
3a-2b/a+b=3*6-2*7/6+7=18-14/13=4/13
