this problem has had my little brain working overtime with no success.
I've been making a weekly budget planner, i have worked out the weekly payment required for each item. i will use an example below of the lay out.

car payment $80pw: week1:$0 week2:$0 week3:$160 week4: etc...

what i've been trying to do is make the default pw payment appear in red if the weekly totals to date dont add up and appear green if they do. so in the example above the $80pw would appear in red as week 3's payment is $80 short.

sorry if this makes no sense, help