1.
(6 - 4 8/15) : 2,2 = (90/15 - 68/15) : 22/10 = 22/15 * 10/22 = 10/15 = 2/3,
2.
(5,4 - 2 1/3) : 7 2/3 = (54/10 - 7/3) : 23/3 = (162/30 - 70/30) * 3/23 = 92/30 * 3/23 = 92/230 = 2/5 (или 0,4);
3.
(7,6 - 4 3/4) : 1,9 = (76/10 - 19/4) : 19/10 = (152/20 - 95/20) * 10/19 = 57/20 * 10/19 = 3/2 = 1ц 1/2 (или 1,5)