-79% is the change from 200 to 42
Calculation steps:
[( 42 - 200 ) ÷ 200] x 100 = -79%
Formula
Percentage change = [(42 - 200) / 200] x 100
Subtract the new number by the original number
42 - 200 = -158
-158 ÷ 200 = -0.79
-0.79 x 100 = -79%
Example