1. The price of one egg tart is $0.90 from Delicious Bakery. For every 3 egg tarts a customer buys, he can buy the fourth one at half the price.
What is the greatest number of egg tarts that a customer can buy with $72?
2. In a hall, there are 16 rows of 19 chairs each. Mr Wong wishes to rearrange these chairs into a square with the same number of chairs on each side. There are no chairs inside the square. How many chairs will there be on each side of the square?
3. The distance between Town A and Town B was 520 km. At , a van left Town A for Town B travelling at a constant speed. At the same time, a car travelling at a constant speed set off from Town B towards Town A. The two vehicles met each other at The car was travelling at 20 km/h faster than the van. What was the speed of the car?
4. A vase and a bottle had a total of 810 mℓ of water. Susan tripled the amount of water in the vase and added 30 mℓ of water into the bottle. The ratio of the amount of water in the vase and bottle is now 9 : 4. How much more water was there in the bottle than in the vase at first?