Answer
Nancy would take 8 hours, and Becky would take 2.67 hours.
Work Step by Step
Becky can complete the job at 1/x jobs per hour, so Nancy could do it at 1/3x jobs per hour. Thus:
$2= 1/x + 1/3x \\ 2 = 4/3x \\ x= 2.67$
It would take Becky 2.67 hours, which means it would take Nancy 3(2.67) = 8 hours.
