23/4 : 1 5/6 + 1 7/8 : (1-5/8)*6 2/5=

2 3/4 :1 5/6 + 1 7/8 :(1-5/8)*6 2/5=33,5
по действиям
2 3/4 :1 5/6= 11/4:11/6=11/4*6/11=6/4=3/2=1 1/2=1,5

1-5/8=3/8

1 7/8:3/8=15/8:3/8=15/8*8/3=15/3=5

5*6 2/5=5*32/5=32

1,5+32=33,5