4 2/3 * 6 - 1 23/42 * 3 1/13 + 2 1/8 * 1 29/51 = 26 4/7,
1) 4 2/3 * 6 = 14/3 * 6 = 28,
2) 1 23/42 * 3 1/13 = 65/42 * 40/13 = 100/21 = 4 16/21,
3) 2 1/8 * 1 29/51 = 17/8 * 80/51 = 10/3 = 3 1/3,
4) 28 - 4 16/21 + 3 1/3 = 27 21/21 - 4 16/21 + 3 7/21 = 26 12/21 = 26 4/7