Task: Question Answering
Input (English): Problem: salad dressing p is made up of 30 % vinegar and 70 % oil , and salad dressing q contains 10 % vinegar and 90 % oil . if the two dressings are combined to produce a salad dressing that is 20 % vinegar , dressing p comprises what percentage of the new dressing ? 
Options: a ) 60 % , b ) 50 % , c ) 40 % , d ) 30 % , e ) 20 %
Output (English): b