I find it easier to plug in numbers for these types of problems. Just a suggestion.
For instance. I made x=10m/s. I did the appropriate conversion, y=36km/hr. I plugged in x to the answer choices to see if any equaled 36. I got C.
Note: when using the "picking numbers" method, it is advised not to use 1. i try to use a larger, yet still easy, number to use, like 5 or 10.
I hope this helps.