9 7/8+5 2/7+1 1/8+4 5/7
1)9 7\8 + 5 2\7 = 9 49\56 + 5 16\56 = 14 49+16 =14 65\56 = 15 9\56
2) 1 1\8 +4 5\7 = 1 7\56 + 4 40\56 = 5 7+40= 5 47\56
3) 15 9\56 + 5 47\56 = 20 9+47 = 20 56\56 = 21