简算下列题目

问题描述:

简算下列题目
2/3-(1/3+1/4)+3/4
5/9-(5/6-2/3)

2/3-(1/3+1/4)+3/4
=8/12-4/12-3/12+9/12
=10/12
=5/6
5/9-(5/6-2/3)
=10/18-15/18+12/18
=7/18