4 целых 5/12-1 целая 1/2:(2 целых 1/5+8/15)х1 целую 4/5=
2 1/5+8/15= 11/5+8/15=33/15+8/15=41/15
1 1/2:41/15=3/2*15/41=45/82
45/82*1 4/5=45/82*9/5=81/82
4 5/12-81/82=53/12-81/82=2173/492-486/492=1687/492=3 211/492