Task: Question Answering
Input (English): Problem: gold is 19 times as heavy as water and copper is 9 times as heavy as water. in what ratio should these be mixed to get an alloy 15 times as heavy as water ?
Options: a. 3: 2, b. 3: 8, c. 5: 7, d. 3: 7, e. 3: 6
Output (English): a