Level 3
Fill in the blanks.
Adam spends 15 of his money on 4 stickers and 5 marbles.
Each marble costs twice as much as each sticker.
Let the cost of 1 sticker be 1 u.
Level 2
Abel can paint a room in 6 hours. Bala can paint the same room in 3 hours. How long will it take for both of them to paint the same room together?