Упростите: 2,8( 4/7m - 0,5 n) - 4/9( 3,6m - 2 целых 1/4n)

2,8( 4/7m - 0,5n) - 4,9(3,6m - 2 целых 1/4n) = 2 целых 8/10 (4/7m - 5/10n) - 4/9( 3 целых 6/10m - 2 целых 1/4n) = (28/10 × 4/7m - 28/10 × 5/10n) - (4/9 × 36/10m - 4/9 × 9/4n) = 8/5m - 7/5n - 8/5m + n = - 0,4n

... = 14\5(4\7m - 1\2n) - 4\9(18\5m - 9\4n) = 8\5m - 7\5n - 8\5m - n = -2 2\5n