8.93-2 又\11-(1又 1/11*4/23+4/23)
=8.93-2 又7\11-(1又/11+1）*4/23
=8.93-2 又7\11-23\11*4/23
=8.93-2 又7\11-4/11
=8.93-（2又7/11+4/11）
=8.93-3
=6.93