4 (целых) 1/5: (7/15:1/3) =

(5 (целых) 8/9 : 1 (целая) 17/36+1 (целая) 1/4) * 5/21 =

4 1/5: (7/15:1/3) = 3

1) 7/15:1/3=7/15*3/1=7/5

2) 4 1/5:7/5=21/5*5/7=21/7=3

(5 8/9:1 17/36+1 1/4) * 5/21=1 1/4

1) 5 8/9:1 17/36=53/9:53/36=53/9*36/53=36/9=4

2) 4+1 1/4=5 1/4

3) 5 1/4*5/21=21/4*5/21=5/4=1 1/4