3.6x31.4+43.9x6.4=3.6x31.4+31.4x6.4+12.5x6.4=31.4x(3.6+6.4)+12.5x8x0.8=314+100x0.8=314+80=39420.05x39+200.5x4.1+40x10.05 = 20.05x39+20.05x41+40x20.05-40x10=20.05x(39+41+40)-400=20.05x120-400=2005+20.0...