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

Time taken by Christopher and Zoey = 10 days ---- (1)
Time taken by Zoey and Mia = 11 days ---- (2)
Time taken by Mia and William = 220% x 10 = 22 days ---- (3)

(1) + (2) + (3)
Christopher + Zoey + Zoey + Mia + Mia + William → 10 + 11 + 22 = 43 days
Christopher + 2 (Zoey + Mia) + William → 43 days
Christopher + William + 2 x 11 → 43 days
Christopher + William → 43 - 22 = 21 days

More days to complete the project for Christopher and William compared to Zoey and Mia
= 21 - 11
= 10

Answer(s): 10