5比x=2.4比1.2 2.4x=5×1.22.4x=6x=6÷2.4x=2.52/3x-1/2x=12 1/6x=12x=12÷1/6x=720.125*32*4 =0.125*8*(4*4)=1*16=16（51-34/39）×1/17=51×1/17-34/39×1/17=3-2/39=2又37/39