2)1 2/3+ 6 4/15+ 8 17/45
4)5 7/20 + 20 4/15 + 12 11/60
6)31 7/9 + 4 11/27 + 35 43/54

Пошаговое объяснение:

2)1 2/3+ 6 4/15+ 8 17/45= 5/3 + 94/15 + 377/45= 75/45 + 282/45+ + +377/45=734/45 = 16 14/45

4)5 7/20 + 20 4/15 + 12 11/60= 107/20 + 304/15 + 83/60= 321/60 + 1216/60 +731/60 = 2268/60 = 37 4/5

6)31 7/9 + 4 11/27 + 35 43/54= 286/9 + 119/27 + 1933/54= 1716/54 + 238/54 +  +1933/54= 3887/54= 71 53/54

2) 16 14/45

4) 37 4/5

6) 71 53/54