Task: Question Answering
Input (English): Problem: if a: b = 3: 4, b: c = 7: 9, c: d = 5: 7, find a: d ?
Options: a. 5 / 12, b. 5 / 15, c. 5 / 10, d. 5 / 11, e. 5 / 13
Output (English): a