Conditional formatting based on another cell's value

Question

I\'m using Google Sheets for a daily dashboard. What I need is to change the background color of cell B5 based on the value of another cell - C5. If C5 is greater than 80%

Answer 1

change the background color of cell B5 based on the value of another cell - C5. If C5 is greater than 80% then the background color is green but if it's below, it will be amber/red.

There is no mention that B5 contains any value so assuming 80% is .8 formatted as percentage without decimals and blank counts as "below":

Select B5, colour "amber/red" with standard fill then Format - Conditional formatting..., Custom formula is and:

=C5>0.8

with green fill and Done.