(1-4/9):(1/3-1/4) и (5/7-2/3):(4/9-5/12)
1)1-4/9=5/9;2)1/3-1/4=1/12;3)5/9:1/12=20/3 ___________________________________ 1)5/7-2/3=1/21; 2)4/9- 5/12=3/108; 3)1/21:3/108=108/63