My math teacher said i can use a calculator and I still dont get it

The problem is the way it is wriiten......it should be :

5/6 - (3 + 2/3)  =

5/6 - 3  - 2/3  =

5/6 - 2/3 - 3  =

5/6 - 4/6  - 3  =

1/6  - 3  =

1/6 - 18/6  =

-17/6

I have a feeling that you subtracted the 3 but  then added the 2/3..........it should have been subtracted.........!!!