Extra $100 after borrowing and shopping I took \$1000 from my friend James and \$500 from Bond.
While walking to the shops I lost \$1000 so now I only have \$500.
I did some shopping, spending \$300 so now I have \$200 left.
I gave \$100 back to James and \$100 back to Bond.
Now my liabilities are \$900 for James and \$400 for Bond, so my total liabilities are \$1300.  
Total liabilities + Shopping = \$1300 + \$300 = \$1600, but I only borrowed \$1500.
Where did the extra \$100 come from?

Total liabilities + shoping = Liability to James + Liability to Bond + Borrowed from Bond $- 200$ 
= Borrowed from James $- 100$ + Borrowed from Bond $-100$ + Borrowed from Bond $- 200$ 
=Borrowed from James + Borrowed from Bond + Borrowed from Bond $- 400$ 
= Borrowed from James + Borrowed from Bond + $100$ 
= Total Borrowed money + $100$
