One way:

Select A3. Choose Format/Conditional Formatting... Set the dropdowns and
textboxes to read

CF1: Formula is =A2=90%
Format1: <patterns/<yellow

In article ,
Matt wrote:

I'm trying to use conditional formatting, but I want to have the format
changed for a different cell than where the data is displaying.

For example, 90% shows up in cell A2, but I want A3 to be highlighted in
yellow. Is this possible? I know going to format -- conditional formatting
allows you to set it up, but only for that particular cell.

Thanks for your help in advance.