1/4 + 2/3 =

7/8 + 2/5 =
4/5 + 1/3 =
1/3 + 1/3 =

1/4 + 2/3 = (3/12) + (8/12) = 11/12

7/8 + 2/5 = (35/40) + (16/40) = 51/40
4/5 + 1/3 = (12/15) + (5/15) = 17/15
1/3 + 1/3 = 2/3