One term I'm not getting in the below..
Q: 5 litres of water is added to a certain quantity of pure milk costing $3 per litre. If, by selling the mixture at the same price as before a profit of 20% is made, what is the amount of pure milk in the mixture?
A: Ok so we have 3x as our cost which should be equal to 1.2(3x) (or 120% of 3x given profit). I would imagine the expression therefore to be 3x + 5 = 1.2(3x). However the solution is 3x + 15 = 1.2(3x). Why 15? (I realize this is 3*5 litres of water but not sure why!).
As usual thanks in advance,