Answer: 
Step-by-step explanation:
This problem can be solved by the <u>Rule of Three</u>, which is a mathematical rule to find out an amount that is with another quantity given in the same relation as other two also known.
In this case, the 25 ounce drink represents the
. So, if Mark drinks 5 ounces, this means he has 20 ounces left and we have to find the percent this represents:
-------
-------- 

This is the percent of the drink Mark has left
B
Here, x is the volume of the 10ml solution. Multiplying it by its concentration gives the amount of alcohol in it. 50 is the total volume of the 12% solution so (50 - x) gives the volume of the 15% solution. Multiplying this by the concentration gives the amount of alcohol in it. The sum of these amounts of alcohols is equivalent to the amount of alcohol in the 12% solution which is given by the product of its volume and concentration.