Answer:
$18.90
Explanation:
Lets break this question down into smaller sections to make it easier:
There are 3 bottles
Each bottle can hold 0.75 liters
For every 25 milliliters she pays $0.21
With that information in mind, we notice that we need to convert liters to milliliters in order to get an accurate answer.
For every 1 liter = 1000 milliliters
So, we need to take 0.75 * 1000 = 750 milliliters per bottle
Next, we take 750 milliliters / 25 milliliters to find how many times we have to fill one bottle
Each bottle will take 30 times of 25 milliliters to fill the whole bottle
Now take 30 * $0.21 to find the cost of one bottle
One bottle = $6.30 to fill
Take $6.30 * 3 to find the total cost to fill ALL the bottles.
For a final result, we get $18.90 to fill all three bottles completely
Hope this Helps!