Найдите сумму: 1) 5 7/8+6 3/10; 2) 6 3/8+ 2 5/9; 3) 1 8/21+4 3/14+2 2/7

5 7/8 + 6 3/10 = 5 70/80 + 6 24/80 = 11 94/80 = 11 47/40 = 12 7/40
6 3/8 + 2 5/9 = 6 27/72 + 2 40/72 = 8 67/72 
1 8/21 + 4 3/14 + 2 2/7 = 1 16/42 + 4 9/42 + 2 12/42 = 7 37/42