Bài 1:
`3/4=(3xx15)/(4xx15)=45/60`
`8/15=(8xx4)/(15xx4)=32/60`
`19/30=(19xx2)/(30xx2)=38/60`
`2/3=(2xx20)/(3xx20)=40/60`
`4/5=(4xx12)/(5xx12)=48/60`
Bài 2:
`a)135135/504504=(135135:1001:9)/(504504:1001:9)=15/56`
`b)135135/368368=(135135:1001)/(368368:1001)=135/368`