If the speed of X meters per second is equivalent to the speed of Y ki

If the speed of X meters per second is equivalent to the speed of Y kilometers per hour, what is Y in terms of X? (1 kilometer=1000 meters)

A. 15x/18
B. 6x/5
C. 18x/5
D. 60x
E. 3600000x

X meters per second -->
--> 3,600X meters per hour (as there are 3,600 seconds in one hour);
--> 3,600X/1,000=18X/5 kilometers per hour (as there are 1,000 meters in one kilometer).

Answer: C.

OR: if you are not comfortable with above manipulations with variable X then you can assume x to be equal to some #: let x=10.

Speed = 10 meters per second -->
--> 10*3,600=36,000 meters per hour -->
--> 36,000/1000=36 kilometers per hour.

So, if x=10, then y=36. Plug x=10 into the answer choices, the one which give 36 will be the correct answer:
A. 15x/18=150/18<36;
B. 6x/5=60/5=12;
C. 18x/5=36 correct choice;
D. 60x=600;
E. 3,600,000x=36,000,000.

Answer: C.