80×5 70×6 решение 1) 400 2)420 3) 400+420
54+46+366 = 466 1000-540 = 460
12+58+430 = 500 900-650 = 250
210+25+45 = 280 880-680 = 200
354+446 = 800 908-78 = 830
947-467 = 480 627-97 = 540
13+987 = 1000 800-25 =775
Π/4-x/2=-π/4+πn, n∈Z
-x/2=-π/2+πn, n∈Z
x=π-πn, n∈Z