计算下面各题（能简便的用简便方法）8/9+7/12+3/45/12+7/8-9/202.85+2/7+2.15+4/73.4-（0.25+2/5）7/8-7/27-20/272.15-（5/6-1/12）11/12+5/8+3/8+1/125-3/7-4/72/5*20+3/5*205/6-1/4+1/3

Question

计算下面各题（能简便的用简便方法） 8/9+7/12+3/4 5/12+7/8-9/20 2.85+2/7+2.15+4/7 3.4-（0.25+2/5）
7/8-7/27-20/27 2.15-（5/6-1/12） 11/12+5/8+3/8+1/12 5-3/7-4/7
2/5*20+3/5*20 5/6-1/4+1/3

Answer 1

8/9+7/12+3/4
=32/36+21/36+27/36
=80/36
=20/9
=2又2/9
5/12+7/8-9/20
=50/120+105/120-54/120
=101/120
2.85+2/7+2.15+4/7
=（2.85+2.15）+2/7+4/7
=5+6/7
=5又6/7
3.4-（0.25+2/5）
=3.4-0.4-0.25
=3-0.25
=2.75
7/8-7/27-20/27
=7/8-（7/27+20/27）
=7/8-1
=-1/8
2.15-（5/6-1/12）
=2.15-3/4
=2.15-0.75
=1.4
11/12+5/8+3/8+1/12
=（11/12+1/12）+（5/8+3/8）
=1+1
=2
5-3/7-4/7
=5-（3/7+4/7）
=5-1
=4
2/5*20+3/5*20
=（2+3）/5*20
=5/5*20
=20
5/6-1/4+1/3
=10/12-3/12+4/12
=11/12