Robert can row a boat at 15 kmph in still water. If the speed of the stream is 4 kmph, what is the time taken to row a distance of 80 km downstream?
Choose the correct option.
A) 80/15 B) 80/17 C) 80/19 D) 80/21 E) 80/23
Speed downstream = 15+4= 
<gadget id="calculator">15+4</gadget>
<output>19</output>
19 kmph.   Time required to cover 60 km downstream= d/s = 80/19 hours. Answer:80/19
<result>C</result>
Robert can row a boat at 15 kmph in still water. If the speed of the stream is 4 kmph, what is the time taken to row a distance of 80 km downstream?