ta có: \(\dfrac{a}{b}=\dfrac{5}{6}\)
=>\(\dfrac{a}{b}=\dfrac{5}{6}=\dfrac{a+5}{b+6}=\dfrac{a-5}{b-6}\)
=>\(\dfrac{a+5}{b+6}=\dfrac{a-5}{b-6}\)
=>\(\dfrac{a+5}{a-5}=\dfrac{b+6}{b-6}\)
Vậy nếu \(\dfrac{a+5}{a-5}=\dfrac{b+6}{b-6}\) thì\(\dfrac{a}{b}=\dfrac{5}{6}\).