EXCEL 問題...求公式?

To display 25%:
=TEXT((8-6)/8,"#0%")
To display 50%:
=TEXT((6-3)/6,"#0%")
You may substitute the first argument with cell reference formula, then you can copy the formula to different cells.

The Excel TEXT function converts a supplied value into text, in a user-specified format.

The format of the function is :
TEXT( value, format_text )

Where the function arguments are:
value - A numeric value, that you want to be converted into text
format_text - A text string that defines the formatting that you want to be applied to the supplied value

The format definitions:
0 - Forces the display of a digit in its place
# - Display digit if it adds to the accuracy of the number (but don't display if a leading zero or a zero at the end of a decimal)
. - Defines the position that the decimal place takes

Example (formula in D2):
=TEXT((C2-B2)/C2,"#0%")