Level 3
Ronnie and Dave, together, can clean a room in 3 hours. If Ronnie is cleaning the room alone, he can only complete the task in 9 hours. How long will Dave take to clean a room all by himself? Express the answer in mixed number.
Level 2
The ratio of the number of blue stickers to red stickers is 5 : 2.
After Adam buys 10 blue stickers and 40 red stickers,
there is an equal number of blue stickers and red stickers.
How many stickers does Adam have now?
Level 2
A container, which is 10 cm long, 9 cm wide and 7.55 cm deep, holds 1510 g of sugar. If 4.95 kg of the same sugar is packed into a tin with a 15-cm square base, how tall must the tin be?