Все (3,9-2,55+4 5/12-1 1/15)/(0,81х8 1/3-0,57: 4 3/4): 2,21+4,125: 2 1/16 !

(3.9 - 2.55 + 4 5/12 - 1 1/15) / (0.81*8 1/3 - 0.57 / 4 3/4) / 2.21 + 4.125/2 1/16 = (3.9 - 2.55 + 53/12 - 16/15) / (0.81 * 25/3 - 0.5 / 19/4) / (2.21 + 4.125 / 33/16) = (1.35 + 265/60 - 64/60) / (81/100 * 25/3 - 2/4 *4/19) / (2.21 + 33/8 / 33/16) =
(1.35 + 201/60) / (27/4 - 2/19) / (2.21 + 33/8*16/33) = (1.35 + 3 21/60) / (512/74 - 8/74) / (2.21 + 2) = (1.35 + 3 21/60) / (504/74) / (4.41) 

(3.9-2.55+4 5/12-1 1/15)/(0,81*8 1/3-0,57:4 3/4):2,21*4,125:2 1/16=~122,916
1) 3,9-2,55=1,35
2) 1,35+4 5/12~3,016
3) ~3,016-1 1/15= 2,95
4) 0,81*8 1/3=2,16
5) 0,57:4 3/4~0,106
6) 2,16-~0,106~2,053
7) ~2,053:2,21=~-0,104
8) 4,125:2 1/16=~0,128
9) ~-0,104+~0,128=~0,024
10) 2,95:~0,024=~122,916