\(\dfrac{4}{5};\dfrac{5}{6}\) và \(\dfrac{6}{7}\)
Mẫu số chung: 210
Ta có:
\(\dfrac{4}{5}=\dfrac{4\times42}{5\times42}=\dfrac{168}{210}\)
\(\dfrac{5}{6}=\dfrac{5\times35}{6\times35}=\dfrac{175}{210}\)
\(\dfrac{6}{7}=\dfrac{6\times30}{7\times30}=\dfrac{180}{210}\)