two percentage word problems!!! No clue!

1) In the chemistry lab I had to mix some 33and1/3 alcohol with some 12and1/2 alcohol to get a 50 litre jug of 25% alcohol. How many litres of the 33and1/3% and of the 12and1/2% alcohol did I use?

2) Harry is trying to quit smoking. He reduced his habit to 1/8 of a carton per week except when he's studying for exams and, being all stressed, then he smokes 1/3 of a carton per week. Over the last 50 weeks, Harry has smoked 1/4 of a carton per week on average. During those 50 weeks, how many weeks did Harry study for exams, and how many weeks did he not study for exams?