So from 1150 to 230 lbs of flour remaining...
The percentage decrease was by
percentage decrease = ((b-a)/b)*100
b is the original value
a is the other value
p= ((1150-230)/1150)*100
p = (920 /1150) * 100
p = (0.8) * 100
p = 80
The percentage decrease is 80% from 1150 to 230 lbs of flour.
Hope this helps :)