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