-78.6% is the change from 645 to 138
Calculation steps:
[( 138 - 645 ) ÷ 645] x 100 = -78.6%
Formula
Percentage change = [(138 - 645) / 645] x 100
Subtract the new number by the original number
138 - 645 = -507
-507 ÷ 645 = -0.786046511627907
-0.786046511627907 x 100 = -78.6%