4. George borrowed N$6000 on the 4th February 2023 at a simple interest rate of 12% per annum. He paid N$2000 on the 21 st April of the same year, N\$1 200 on the 12th May of the same year and N\$1 400 on the 11th June of the same year. What was the balance due on the 15th August of the same year if payments were subject to the same simple interest as the original debt. [6]