Answer:
There were approximately 53 cases of measles before the increase.
Step-by-step explanation:
Since there was an increase of 10.2% this means that the value we have now is the value we had prior plus the increase, in other words this is 100% of the cases before the increase plus 10.2%, so we have now 110.2% of cases. We know that this value represents 58 cases, so we can use a rule of three in order to determine the prior value. This is seen bellow:
100% -> x
110.2% -> 58
110.2*x = 100*58
x = 5800/110.2 = 52.63
Which is approximately 53 cases.