(12 3/8:2 1/16-5 5/21)*7/8+3 2/15
пишу по действиям
12 3/8 = 99/8
2 1/16 = 33/16
5 5/21 = 110/21
3 2/15 = 47/15
12 3/8:2 1/16 = 99/8 : 33/16 = 99/8 * 16/33 =99/33*16/8 = 3*2= 6
6 - 110/21 = (126-110)/21 = 16/21
16/21 *7/8 = 16/8 *7/21 = 2/3
2/3 +47/15 = 10/15 +47/15 =57/15 =19/5 = 3 4/5
ответ 3 4/5