-9.87% is the change from 709 to 639
Calculation steps:
[( 639 - 709 ) ÷ 709] x 100 = -9.87%
Formula
Percentage change = [(639 - 709) / 709] x 100
Subtract the new number by the original number
639 - 709 = -70
-70 ÷ 709 = -0.09873060648801128
-0.09873060648801128 x 100 = -9.87%