I have a spreadsheet that i need to use to calculate children's reading ages
against their real ages with a 6 month swing either way, using a 3 colour
system.

For example. if a child is 8 years and 6 months old (Cell Ref B4 and listed
as a 2 decimal point number), and their reading age is in the range 8 years
to 9 year 2 months, I need that to show amber. If it's one month either side
of that range, i need it to show red if it's under and green if it's over.

I've got it working with specific number using less than, equal to or
greater than formuals, but it will only show amber for the exact DOB ie if a
child is 8.6 in B4, it will only show amber if the number in C4 is identical.

Does this make sense?

I also need to figure out how to create a custom format to take into account
there are 12 months in a year and not just 10 when using normal numbers.

Any help would be supremely appreiciated