(1,8*0,4-2 8/15:6 1/3):(-0,8)
(1,8*0,4-2 8/15:6 1/3):(-0,8) = (18/10*4/10-38/15:19/3):(-0,8) = (18/25-38/15*3/19):(-8/10) = (18/25-2/5)*(-10/8) = (18/25-10/25)*(-10/8) = 8/25*(-10/8) = -2/5 = -0,4