Answer:
with the way you wrote it, it's unidentified
Change in value= new price-original price
Change in value=850-10000
Change in value= -9150
%decreased=change in value/original price x 100
%decreased= 9150/10000x100
The answer is 91.5%
If 0.3 = 1 then 0.9 = 3 because 0.3+0.3+0.3=the 3.