-62.5% is the change from 136 to 51
Calculation steps:
[( 51 - 136 ) ÷ 136] x 100 = -62.5%
Formula
Percentage change = [(51 - 136) / 136] x 100
Subtract the new number by the original number
51 - 136 = -85
-85 ÷ 136 = -0.625
-0.625 x 100 = -62.5%
Example