3/8 + 1/4, 2/3 - 1/6, 7/12 - 1/2, 2/9 + 2/3

1). 3/8 + 1/4 = 3/8 + 2/8 = 5/8
2). 2/3 - 1/6 = 4/6 - 1/6 = 3/6 = 1/2
3). 7/12 - 1/2 = 7/12 - 6/12 = 1/12
4). 2/9 + 2/3 = 2/9 + 6/9 = 8/9.
не за что

3/8 + 1/4 = 5/8
2/3 - 1/6 = 3/6 = 1/2
7/12 - 1/2 = 1/12
2/9 + 2/3 = 8/9