5/6－3/4+1/3
=10/12-9/12+4/12
=5/12
11/12－(1/6－1/8)
=22/24-4/24+3/24
=21/24
=7/8
7/12－(3/4－1/2)
=7/12-1/4
=1/3
1/2－(3/4－3/8）
=1/2-3/8
=1/8
如果本题有什么不明白可以追问,