А) ((49•16)/(8•7) – 239/19):27+18/19 =
= 27/(19•27)+18/19 = 1/19+18/19 = 1
б) ((15•7)/(4•30)+1/8):4/5–9/4 =
= (7/8+1/8):4/5–9/4 = 5/4–9/4 = 1
в) (5/9–11/2):89/11•18/5 = (-89•11•18)/(18•89•5) = –11/5
г) (21/2–11)^2•(20–64/3)–17/3 =
= 1/4•(-4/3)–17/3= –1/3–17/3 = –18/3 = = -6