Fiona bought some oranges and 8 mangoes for a total of $30.80. For every mango Fiona bought, she could buy 4 oranges with the same amount of
money. A mango cost $2.10 more than an orange.

30,000 mg

Step-by-step explanation:

In this case what we should do multiply the daily quantity by the number of days, that is:

They tell us that the daily amount is 500 milligrams, that is, 500 mg / day.

Now, the total time they tell us is 60 days, so we have:

500 mg / day * 60 day = 30,000 mg

That is, a total of 30,000 milligrams of chlorine in the 60 days.