1. 2 18/31 * 12 2/5 - 2 3/4 : 33/7 = 80/31 * 62/5 - 11/4 * 7/33 = 32 - 7/12 = 377/12 = 31 5/12
2. 5/3 * 3 3/5 + 26/9 : 19 1/2 = 5/3*18/3 + 26/9 * 2/39 = 15+52/351 = 15 52/351
3. 68/55 : 3/33 : 96/100 - 0,35 = 68/55 * 33/34 * 100/96 - 0,35 = 20/16 - 0,35 = 1,25-0,35 = 0,9
4.