If Nora and Ethan work together on a project, they will complete it in 10 days. If Ethan were to work with Harper on the same project, they will take a day longer. If Harper and Hannah work together, they will take 120% more time than Nora and Ethan. If Nora and Hannah were to work together, how many more days will they take to complete the project compared to Ethan and Harper working together?
Time taken by Nora and Ethan in percent = 100%
Time taken by Harper and Hannah = 100% + 120% = 220%

Time taken by Nora and Ethan = 10 days ---- (1)
Time taken by Ethan and Harper = 11 days ---- (2)
Time taken by Harper and Hannah = 220% x 10 = 22 days ---- (3)

(1) + (2) + (3)
Nora + Ethan + Ethan + Harper + Harper + Hannah → 10 + 11 + 22 = 43 days
Nora + 2 (Ethan + Harper) + Hannah → 43 days
Nora + Hannah + 2 x 11 → 43 days
Nora + Hannah → 43 - 22 = 21 days

More days to complete the project for Nora and Hannah compared to Ethan and Harper
= 21 - 11
= 10

Answer(s): 10