Này, bnaj theo dõi mk đc hem
Bn, ơi, theo dõi mk ddc hem
`x : 3/5 = 7/9`
`x = 7/9 xx 3/5`
`x = 7/15`
`x xx 2/5 = 4/6`
`x = 4/6 : 2/5`
`x = 20/12`
`x = 5/3`