98.49-65.82+72.51-12.12 =98.49+72.51-12.12 -65.82=98+72+0.49+0.51-﹙12.12 +65.82﹚
=171-﹙12+65+0.12+0.82﹚=171-﹙77+0.94﹚=94-0.94=93.06