1) 5/6*7/9 11/28*7/33 1 8/25*1 4/13 3 5/7*1 1/13 2) 1 5/19 * (6-3 5/8) 1,8 * (6,3*1,4-2,05)

1) 5/6 * 7/9 = (5 * 7) / (6 * 9) = 35/54;

11/28 * 7/33 = (11 * 7) / (28 * 33) = 1 / (4 * 3) = 1/12;

1 8/25 * 1 4/13 = (1 * 25 + 8) / 25 * (1 * 13 + 4) / 13 = 33/25 * 17/13 = (33 * 17) / (25 * 13) = 561/325;

3 5/7 * 1 1/13 = (3 * 7 + 5) / 7 * (1 * 13 + 1) / 13 = 26/7 * 14/13 = 4;

2) 1 5/19 * (6 - 3 5/8) = (1 * 19 + 5) / 19 * (6 - (3 * 8 + 5) / 8) = 24/19 * (6 - 29/8) = 24/19 * 19/8 = 24/8 = 3;

1,8 * (6,3 * 1,4 - 2,05) = 18/10 * (63/10 * 14/10 - 205/100) = 9/5 * (882/100 - 205/100) = 9/5 * 677/100 = (9 * 677) / 500 = 6093/500 = 12,186.