Answer:
x² - 20 = 0
Using the quadratic formula

a = 1 b = 0 c = -20
So we have

Hope this helps you.
100% = 1600
120% = 1920
1920/120 = 1536/y
1920y = <span>184320 (cross multiply)
y = 96%
decrease of 24% from 1920</span>
I need to see the graphs, can you attach a image of them..