2 câu trả lời
$1$`)` `4 : 2/5 = 4 × 5/2 = 20/2 = 10`
$2$`)` `1/2 × 1/4 = {1 × 1}/{2 × 4} = 1/8`
$3$`)` `3 × 4/7 = {3×4}/{7} = 12/7`
$4$`)` `3/5 × 5 = {3 × 5}/{5} = 15/5 = 3`
`4 : 2/5 = 4 xx 5/2 = 10`
`1/2 xx 1/4 = (1xx1)/(2xx4) = 1/8`
`3 xx 4/7 = (3xx4)/7 = 12/7`
`3/5 xx 5 = (3xx5) / 5 = 3`