-40% is the change from 900 to 540
Calculation steps:
[( 540 - 900 ) ÷ 900] x 100 = -40%
Formula
Percentage change = [(540 - 900) / 900] x 100
Subtract the new number by the original number
540 - 900 = -360
-360 ÷ 900 = -0.4
-0.4 x 100 = -40%
Example