If Ryan and Zoe work together on a project, they will complete it in 10 days. If Zoe were to work with Oliver on the same project, they will take a day longer. If Oliver and Risa work together, they will take 150% more time than Ryan and Zoe. If Ryan and Risa were to work together, how many more days will they take to complete the project compared to Zoe and Oliver working together?
Time taken by Ryan and Zoe in percent = 100%
Time taken by Oliver and Risa = 100% + 150% = 250%

Time taken by Ryan and Zoe = 10 days ---- (1)
Time taken by Zoe and Oliver = 11 days ---- (2)
Time taken by Oliver and Risa = 250% x 10 = 25 days ---- (3)

(1) + (2) + (3)
Ryan + Zoe + Zoe + Oliver + Oliver + Risa → 10 + 11 + 25 = 46 days
Ryan + 2 (Zoe + Oliver) + Risa → 46 days
Ryan + Risa + 2 x 11 → 46 days
Ryan + Risa → 46 - 22 = 24 days

More days to complete the project for Ryan and Risa compared to Zoe and Oliver
= 24 - 11
= 13

Answer(s): 13