2又3/4-{5又1/4-【0.04-(1又5/8-2又1/5)-0.1】+1/5}

问题描述:

2又3/4-{5又1/4-【0.04-(1又5/8-2又1/5)-0.1】+1/5}

2又3/4-{5又1/4-【0.04-(1又5/8-2又1/5)-0.1】+1/5}
=2又3/4-5又1/4+【0.04-(1又5/8-2又1/5)-0.1】-1/5
=(2又3/4-5又1/4)+0.04-(1又5/8-2又1/5)-0.1+1/5
=-2又1/2+0.04-1又5/8+2又1/5-0.1+1/5
=(-2又1/2-1又5/8)+(0.04-0.1)+(2又1/5+1/5)
=-4又1/8-0.06+2又2/5
=-4.125-0.06+2.4
=-1.785