Salut,
[tex]\dfrac{5a}{7b}=\dfrac{1}{21}\Rightarrow \dfrac{5}7\cdot\dfrac{a}b=\dfrac1{21}\Rightarrow\dfrac{a}b=\dfrac{1}{21}\cdot\dfrac{7}5=\dfrac{7}{3\cdot 7\cdot 5}=\dfrac{1}{15}.[/tex]
[tex]\boxed{\dfrac{a}b=\dfrac{1}{15}.}[/tex]
A fost greu ?
Green eyes.
