Question

How do i calculate Percentage change in Area?

Answer 1

The formula is
old % - new % - (old % x new %)/100

Suppose, 

Old % = 15%, New = 10%
x+y+xy/100

15-10-(150/100)

15-10-1.5 = 3.5% increase.

The positive sign of 3.5 indicates an increase.