Oracle SQL query for recursive calculation

I have a table with four columns.
column names are po_line_num,receipt_num, bal_inv_amt, total_write_off_amt.

In above example i need sql logic for Column G.

For first row, result should be 200 (E5-D5)

For second row, result should be 0 (G5-D6)

For Third row, result should be 0 (G6-D7)

Please share sample query if anyone gone through this scenario.