а) (3/4 + 1/6) * 3 + (5/6 - 1/2) / 2/9 =(9/12 + 2/12) * 3 + (5/6 - 3/6) / 2/9 =
=11/12 *3 + 2/6 / 2/9 = 33/12 + 18/12 = 51/18 = 2 15/18 = 2 5/6
б) (1 1/5 + 2 3/10) : 1/2 + (6 3/4 - 2 2/3) / 1 1/6 = (12/10 + 23/10) / 1/2 + (27/4 - 8/3) / 7/6 = 35/10 / 1/2 + (81/12 - 32/12) / 7/6 = 35/20 + 49/12 / 7/6 = 35/20 + 294/84 = 35/20 + 70/20 = 105/20 = 5 1/4