The task is to generate the correct answer for a given math problem.
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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: excluding stoppages , the average speed of a bus is 60 km / hr and including stoppages , the average speed of the bus is 15 km / hr . for how many minutes does the bus stop per hour ?

Answer: 4


Question: Problem: if 4 / ( 1 + 3 / x ) = 1 , then x =

Answer:
1