barbie5878, hello
Think of it this way....
The net decrease is in fact: x/100
To find what percent of the original number that net decrease is, we put the net decrease in the numerator and put the original number in the denominator and then multiply the result by 100 to get a percent. Let's do that...
Net decrease percent = \({{x\over 100} \over x} 100\)
Okay? But that just becomes: \({x\over 100} {1\over x} 100\)
Yes? Please let me know if this helped at all.