Well, we already know that it took Jen, 3 hours, by herself to complete half the work. Then, together they both completed it in half an hour. Now, you must summarize your given data.
3 hours = Half of the work for Jen
30 Minutes = Jen and Maryna Together To Finish
If the two girls were working at the same pace, it would take them an hour and a half. However, it only took them 30 minutes to complete that. Now, we realize that Maryna works 3x faster than Jen does.
The question is asking, how long would it take her to FINISH the job.
So that means, we must divide 3 by Jen's time.
3 / 3 = 1
So, that means that it would only take Maryna 1 hour to complete the rest of the job.
