Cindy paddles her kayak upstream at c kilometers per hour, and then returns downstream the same distance at n kilometers per hour. How many kilometers upstream did she travel if she spent a total of p hours for the round trip? Choose the most appropriate option
A) cnp B) cn/p C) (c + n)/p D) cnp/(c + n) E) pm/n- pn/m
let t1 and t2 be the time taken to row upstream and downstream respectively   now,   t1=distance/speed=d/c   similarly,   t2=d/n (as same distance has to be rowed)   also,   t1+t2=p   therefore,   p=(d/c)+(d/n)   =d(c+n)/cn   d=pcn/(c+n)=cnp/(c + n)
<result>D</result>
Cindy paddles her kayak upstream at c kilometers per hour, and then returns downstream the same distance at n kilometers per hour. How many kilometers upstream did she travel if she spent a total of p hours for the round trip?