3 5/6*15/23+15/28:4 2/7=
3 5/6*15/23+15/28:4 2/7=2 5/8 или 2,625 1) 3 5/6*15/23 = 23/6*15/23 = 15/6 = 5/2 = 2 1/2 2) 15/28:4 2/7 = 15/28:30/7 = 15/28*7/30 = 1/8 3) 2 1/2+1/8 = 5/2+1/8=20/8+1/8=21/8 = 2 5/8 или 2,625