(3,8:9,5+3,9:1,5-1 5/8):0,75

 (3,8:9,5+3,9:1,5-1 5/8):0,75 = (0.4 + 2.6 - 13/8) : 3/4 = (3 - 13/8)  : 6/8 = 11/8 : 6/8 = 11/6 = 1 5/6;