`text{a ) Cách 1 :}`
`2/3 : 4/5 : 7/6 = 5/6 : 7/6 = 5/7`
`text{Cách 2 :}`
`2/3 : 4/5 : 7/6 = 2/3 × 5/4 × 6/7 = {2 × 5 × 6}/{3 × 4 × 7} = 60/84 = 5/7`
`text{b ) Cách 1 :}`
`2/3 : 4/3 : 5/4 = 1/2 : 5/4 = 2/5`
`text{Cách 2 :}`
`2/3 : 4/3 : 5/4 = 2/3 × 3/4 × 4/5 = {2 × 3 × 4}/{3 × 4 × 5} = 2/5`
`text{c ) Cách 1 :}`
`2 : 2/3 : 3/4 = 3 : 3/4 = 4`
`text{Cách 2 :}`
`2 : 2/3 : 3/4 = 2/1 × 3/2 × 4/3 = {2 × 3 × 4}/{1 × 2 × 3} = 4/1 = 4`
`#dtkc`