Answer: If the new or compared value is P% more than the reference value, you can calculate the reference value as follows:
Reference value = New or compared value / (1 + P/100)
For example, if the new value is 120% of the reference value, then P = 20 and the reference value can be calculated as:
Reference value = New value / (1 + 20/100) = New value / 1.2
If the new or compared value is P% less than the reference value, you can calculate the reference value as follows:
Reference value = New or compared value / (1 - P/100)
For example, if the new value is 80% of the reference value, then P = 20 and the reference value can be calculated as:
Reference value = New value / (1 - 20/100) = New value / 0.8
Explanation: