8-4,2: (2 8/14 - 1 6/21) сравните дроби 4/6 и 3/3 и 5/4 6/8 0,4 (3m - 5)-0,5(5m-7)

8-4,2:(2 8/14 - 1 6/21)=8-4,2:(2 24/42-1 12/42)=4-4,2:1 12/42=4-3 4/15=11/15

Сравните дроби 4/6 и 3/3 и 5/4 6/8
4/6<3/3 (4/6<1);    5/4>6/8  (1 1/4>6/8)

0,4 (3m - 5)-0,5(5m-7) =1.2m-2-2.5m+3.5=-1.3m+1.5