-86.96% is the change from 391 to 51
Calculation steps:
[( 51 - 391 ) ÷ 391] x 100 = -86.96%
Formula
Percentage change = [(51 - 391) / 391] x 100
Subtract the new number by the original number
51 - 391 = -340
-340 ÷ 391 = -0.8695652173913043
-0.8695652173913043 x 100 = -86.96%