Task: Question Answering
Input (English): Problem: solution a is 20 % barium and solution b is 80 % barium . if you have 30 ounces of solution a and 60 ounces of solution b , in what ratio could you mix solution a with solution b to produce 50 ounces of a 50 % barium solution ? 
Options: a ) 6 : 4 , b ) 6 : 14 , c ) 4 : 4 , d ) 4 : 6 , e ) 3 : 7
Output (English): c