-30.01% is the change from 913 to 639
Calculation steps:
[( 639 - 913 ) ÷ 913] x 100 = -30.01%
Formula
Percentage change = [(639 - 913) / 913] x 100
Subtract the new number by the original number
639 - 913 = -274
-274 ÷ 913 = -0.30010952902519167
-0.30010952902519167 x 100 = -30.01%