A boat can move upstream at 22 kmph and downstream at 42 kmph, then the speed of the current is?
Choose one:
A) 15	B) 16	C) 18	D) 10	E) 12
US = 22   10S = 42   M = (42 - 22)/2= 
<gadget id="calculator">(42 - 22)/2</gadget>
<output>10</output>
10 Answer:10
<result>D</result>
A boat can move upstream at 22 kmph and downstream at 42 kmph, then the speed of the current is?