Leave cell empty even when there is a formula in it.

Hi there,

Its probably very simple question, but i can not work it out.

I am trying to design a simple worksheet so I can keep track of how much money my room mate has paid me and what she owes. She pays $142 a week rent plus $23 a month for internet.

Please open the attached workbook. You can see in E7 and 8 there is a red negative number. This is because my tenant hasn't paid me yet for those weeks (D7 & 8).

How can i get these cells to read $0 or leave the cell empty??

The reason why I need this to read $0 or nothing is because it is messing up my next calculation in D3 where it works out how much she has paid for our internet bill.

Thanking you in advance. And sorry if this is a really daft question. Its probably something really simple i have missed.

Thanks

Monique