Level 3 The number of boys and girls in a hall were in the ratio 2 : 7. After 15 boys entered the hall and half the number of girls left the hall, the ratio of the number of boys to girls became 1 : 1. How many children were there in the hall at first?
Level 2 PSLE
Mr Chen bought some goldfish at $10 each. He also bought an equal number of swordfish at a different price. The average price of the goldfish and the swordfish was $8. Mr Chen paid $36 more for the goldfish than the swordfish he bought. How many goldfish did he buy?