-18.92% is the change from 666 to 540
Calculation steps:
[( 540 - 666 ) ÷ 666] x 100 = -18.92%
Formula
Percentage change = [(540 - 666) / 666] x 100
Subtract the new number by the original number
540 - 666 = -126
-126 ÷ 666 = -0.1891891891891892
-0.1891891891891892 x 100 = -18.92%