七又九十七分之二×1.1－6.81×九十七分之九＋68.1÷五又十九分之二＝681/97×11/10-6.81×9/97+68.1/(97/19)＝68.1×11/97-68.1×0.9/97+68.1×19/97＝68.1×(11/97-0.9/97+19/97)＝68.1×29.1/97＝68.1×0.3＝20.4...