(24/30)*100 = 80%
Therefore she decreased from 100% to 80%, which is about 20% decrease.
Thus, the answer is 20%
Another way to do this is.
\(\frac{(Original value - current value)}{Original value} * 100% = percentage of change in value\)
Which in this case is
\(\frac{30-24}{30} * 100% = 20%\)
