Anita can clean 1/8 portion of the pool in 1 hour
Chao can clean 1/6 portion of the pool in 1 hour
Both of them working together can clean 1/8 + 1/6 = 7/24 portion of the pool in 1 hour
Therefore, it will take both of the working together 1/(7/24) = 24/7 or 3 3/7 hours to clean a typical pool.
Answer:
3
Step-by-step explanation:
63/21 = 3
Estimating the area:

Calculating wallpaper:

we round up here because they will need a full roll to complete the room. Since they can't buy 7.92 rolls, they must buy 8.
Calculating cost:
i am pretty sure the answer is 9