1)
5 3/7 * 3/8 = 38/7 * 3/8 = 57/28 = 2 1/28,
2)
5 1/4 : 7 = 21/4 * 1/7 = 3/4,
3)
2 1/28 - 3/4 = 1 29/28 - 21/28 = 1 8/28 = 1 2/7,
4)
1 2/7 : 3 = 9/7 * 1/3 = 3/7,
5)
3/7 + 3 3/28 = 12/28 + 3 3/28 = 3 15/28,
6)
3 15/28 - 1/2 = 3 15/28 - 14/28 = 3 1/28