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.
The answer is x = 2 which is b
