3/7+1/2-3/7简便计算5/7-1/6+5/14简便计算7/12-（5/6-5/12）简便计算2/3-1/2-1/

3/7+1/2-3/7简便计算
=(3/7-3/7)+1/2
=1/2;
5/7-1/6+5/14简便计算7
=(10/14+5/14)-1/6
=15/14-1/6
=90/84-14/84
=76/84;
=19/21;
7/12-（5/6-5/12）简便计算
=(7/12+5/12)-5/6
=1-5/6
=1/6;
2/3-1/2-1/18
=12/18-9/18-1/18
=2/18
=1/9;
2X-1/8=7/8
2x=1;
x=1/2;
X-1/9-8/9=2 解方程
x-1=2;
x=3;
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3/7 + 1/2 - 3/7
= 3/7 - 3/7 + 1/2
= 1/2
5/7 - 1/6 + 5/14
= 10/14 + 5/14 - 1/6
= 1 + 1/14 - 1 + 5/6
= 3/42 + 35/42
= 38/42
= 19/21
7/12 - ( 5/6 - 5/12 )
= 7/...