-19.4% is the change from 670 to 540
Calculation steps:
[( 540 - 670 ) ÷ 670] x 100 = -19.4%
Formula
Percentage change = [(540 - 670) / 670] x 100
Subtract the new number by the original number
540 - 670 = -130
-130 ÷ 670 = -0.19402985074626866
-0.19402985074626866 x 100 = -19.4%