Answer:
558
Step-by-step explanation:
The original number of cases of measles was x.
x was 100% of the number of cases of measles.
The number of cases then went down by 9%.
100% - 9% = 91%
The number of cases now is 91% of the original number, or 91% of x. We are told the number now is 508, so 91% of x must equal 508.
91% of x = 508
0.91x = 508
x = 508/0.91
x = 558.241...
Answer: 558
