Task: Question Answering
Input (English): Problem: the cost of 3 pens and 5 pencils is rs. 150. also the cost of one pen and one pencil is in the ratio of 5: 1 respectively. what is the cost of one dozen pens ?
Options: a. rs. 200, b. rs. 250, c. rs. 300, d. rs. 450, e. none of these
Output (English): d