How to borrow if you can't subtract from the lowest number on top

Go to the number next to the one you cannot subtract from, take one away, and add a one in front of the number you cannot subtract from. e.g. 
27      1(1)7             the answer would be 9
-8             -8

for your problem the answer would be 1109

           8  1
      7898
   -  6789
     
       1109    is your answer
  And to borrow you just subtract from the number before it and add 10 

Thats where they was ported and the fields that noone really knew much about needed tended, so they put slaves out there do free work and huge profits and so on the north decided to hold its own and was more different way of survival did not have same climate conditions to afford protecting slaves from winter so expenses be diff from south