3 3/12 +5/12; 3 3/12+1 5/12

3 3\12+5\12 = 3+(3\12+5\12) = 3+8\12 = 3+2\3 = 3 2\3
3 3\12+1 5\12 = 3+1+(3\12+5\12) = 4 8\12 = 4 2\3