if Juan takes 12 seconds to run y yards, how many seconds will it take him to run x yards at the same rate? Choose the correct choice:
A) 11x/y B) 11y/x C) x/11y D) 12x/y E) xy/11
Answer is D   The rate of running hards: 12 minutes per y hards.   Thus the time for running x hards = x hards * 12 minutes/y hards = 12x/y
<result>D</result>
if Juan takes 12 seconds to run y yards, how many seconds will it take him to run x yards at the same rate?