-89.61% is the change from 770 to 80
Calculation steps:
[( 80 - 770 ) ÷ 770] x 100 = -89.61%
Formula
Percentage change = [(80 - 770) / 770] x 100
Subtract the new number by the original number
80 - 770 = -690
-690 ÷ 770 = -0.8961038961038961
-0.8961038961038961 x 100 = -89.61%