If u can help to solve it

Today i received an interesting question through SMS. It looked simple in first glance but actually it proved to be tricky. I invite you to solve the following situation.

Problem
Person A took loan of Rs 1000 and 500 from his friends B and C respectively.
Later A payed 1000 to some one else.
Out of remaining 500 A gave back 100 each to B and C.
And also purchased some goods of Rs 300.
Now person A has to pay 900 (1000-100) to B and 400 (500-100) to C.
It makes 900 + 400 = 1300. On the other hand person A has purchased goods of 300.
The total goes to 1600 (1300 + 300).
While the total was expected to be 1500, the amount which was borrowed.

So could u help to solve the equation that why amount exceeds to 1600?