75%-4又2/3-3又4/9×0.25÷2又5/6+1又1/3÷2又1/2=75%-4又2/3-31/36÷2又5/6+2/3=75%-（4又2/3-2/3）-31/102=75%-4-31/102=-3又1/4-31/102=-3又113/204
