( 11  5/6 - 13  6/6):26/10 + (7  1/3 - 10  6/10)* 15/7    

---------------------------------------------------------------- =

               -13:26/10  + 12 5/6

-2  1/6 * 10/26 + (7 10/30 - 10 18/30)*15/7

---------------------------------------------------------=

              -13*10/26+12 5/6

-13/6*10/26+(-3  8/30)*15/7

-------------------------------------=

    11  11/6- 4  6/6

-5/6  + (-98/30)*15/7

----------------------------=

     7  5/6

-5/6+(-7)

------------=

7 5/6

-7.  5/6

---------=-1

7  5/6