The speed of a boat in upstream is 30 kmph and the speed of the boat downstream is 70 kmph. Find the speed of the boat in still water and the speed of the stream? Choose the most appropriate option:
A) 10 kmph
B) 20 kmph
C) 12 kmph
D) 97 kmph
E) 15 kmph
Speed of the boat in still water   = (30+70)/2= 
<gadget id="calculator">(30+70)/2</gadget>
<output>50</output>
50 kmph. Speed of the stream= (70-30)/2= 
<gadget id="calculator">(70-30)/2</gadget>
<output>20</output>
20 kmph.   Answer: 20 kmph
<result>B</result>
The speed of a boat in upstream is 30 kmph and the speed of the boat downstream is 70 kmph. Find the speed of the boat in still water and the speed of the stream?