Answer:
1/40
Step-by-step explanation:
<h3 />
The <em>correct answer</em> is:
C) x/21
Explanation:
Since Person 1 can complete the entire job (100% = 1/1 = 1) in 21 minutes, this person can complete 1/21 of the job per minute. This is Person 1's rate. If x is the amount of time it takes both people together to finish the job, then the amount of work Person 1 does would be (1/21)(x) = x/21.
We can solve this problem by dividing 9/12 by 2/12. We should do this because to find how many sets of something are in a number, the question is asking us to do division. Doing this, we get 9/12 * 12/2, giving us our answer of 4.5 sets of 2/12 in 9/12.
