А))) по действиям...
(-10/21)*(-14/25)*(5/8) = (10*14*5) / (21*25*8) = (2*2) / (3*8) = 1/6
(-24/35)*(15/28)*(49/60) = -(24*15*49) / (35*28*60) = -(24) / (5*4*4) = -3/10
(-25/32)*(-8/55)*(-44/75) = -(25*8*44) / (32*55*75) = -(5*8*4) / (32*75) = -1/15
-3/10 - 1/15 = -9/30 - 2/30 = -11/30
1/6 - 11/30 = 5/30 - 11/30 = -6/30 = -1/5 = -0.2
b)))
(-27/8)*(16/9)*(-5/4) = (27*16*5) / (8*9*4) = (3*2*5) / (4) = 15/2
(8/3)*(-25/16)*(-5/3) = (8*25*5) / (3*16*3) = 125 / 18
(-15/8)*(-11/5)*(-10/3) = -(15*11*10) / (8*5*3) = -55/4
15/2 + 125/18 = 135/18 + 125/18 = 260/18 = 130/9
130/9 - 55/4 = 520/36 - 495/36 = 25/36