The percentage increase/decrease from initial value (Vinitial) to final value (Vfinal) is equal to the initial and final values difference divided by the initial value times 100%:
Price percentage increase from initial value of $1000 to final value of $1200 is caluclated by:
Price percentage increase from initial value of $1000 to final value of $800 is caluclated by:
So
percentage decrease = 20%
The difference d is equal to the initial value Vinitial times the percentage increase/decrease p divided by 100:
The final value Vfinal is equal to the initial value Vinitial plus the difference d:
Vfinal = Vinitial + d
Here's the formula:
Percentage Increase = ((Final Value - Initial Value) / Initial Value) * 100