A boat can move upstream at 15 kmph and downstream at 75 kmph, then the speed of the current is?  Choose the correct choice from the following answers: A) 30 B) 20 C) 45 D) 10 E) 20
US = 15   DS = 75   M = (75- 15)/2= 
<gadget id="calculator">(75- 15)/2</gadget>
<output>30</output>
30   30nswer:30
<result>A</result>
A boat can move upstream at 15 kmph and downstream at 75 kmph, then the speed of the current is?