A man rows his boat 90 km downstream and 70 km upstream, taking 3 hours each time. Find the speed of the stream?	Choose the correct answer.
A) 76 kmph  B) 6 kmph  C) 3.5 kmph  D) 4.5 kmph  E) 4 kmph
Speed downstream = d/t = 90/(3)= 
<gadget id="calculator">90/(3)</gadget>
<output>30</output>
30 kmph   Speed upstream= d/t = 70/(3)   = 23 kmph   The speed of the stream = (30 - 23)/2= 
<gadget id="calculator">(30 - 23)/2</gadget>
<output>7/2 = around 3.5</output>
3.5 kmph   Answer:3.5 kmph
<result>C</result>
A man rows his boat 90 km downstream and 70 km upstream, taking 3 hours each time. Find the speed of the stream?