(2 7/12 + 1 7/15) * 1 1/9 - 1 7/8 = 2 5/8 (или 2,625),.
1) 2 7/12 + 1 7/15= 31/12 + 22/15= 155/60 + 88/60= 243/60= 4 1/20 (или 4,05),
2) 4 1/20 * 1 1/9 = 81/20 * 10/9 = 9/2 = 4 1/2 (или 4,5),
3) 4 1/2 - 1 7/8 = 9/2 - 15/8 = 36/8 - 15/8 = 21/8 = 2 5/8
(или 4,5 - 1 7/8 = 4,5 - 1,875 = 2,625)