instruction:
The task is to generate the correct answer for a given math problem.
question:
Problem: a man rows his boat 110 km downstream and 90 km upstream , taking 3 hours each time . find the speed of the stream ?
answer:
3.5


question:
Problem: if p / q = 3 / 11 , then 2 p + q = ?
answer:
17


question:
Problem: the ratio of the volumes of two cubes is 729 : 125 . what is the ratio of their total surface areas ?
answer:

81 : 25