a ) Cách `1`
`5/24 × 5/12 × 24`
`= {5 × 5 × 24}/{24 × 12 × 1}`
`= {5 × 5}/{12 × 1}`
`= 25/12`
Cách `2`
`5/24 × 5/12 × 24`
`= ( 5/24 × 24 ) × 5/12`
`= 5 × 5/12`
`= 25/12`
b ) Cách `1`
`( 1/4 + 2/3 ) × 4/5`
`= 11/12 × 4/5`
`= 44/60 = 11/15`
Cách `2`
`( 1/4 + 2/3 ) × 4/5`
`= 1/4 × 4/5 + 2/3 × 4/5`
`= 1/5 + 8/15`
`= 11/15`
c ) Cách `1`
`3/7 × 16/33 + 16/33 × 4/7`
`= 48/231 + 64/231`
`= 112/231 = 16/33`
Cách `2`
`3/7 × 16/33 + 16/33 × 4/7`
`= 16/33 × ( 3/7 + 4/7 )`
`= 16/33 × 1`
`= 16/33`
`#dtkc`
