Level 3
At first, the ratio of the number of boys to the number of girls at a school playground was 2 : 5. When 48 girls and some boys entered the playground, the number of girls increased by 12% and the total number of children at the playground increased by 20%.
How many boys were there at first?
What percentage of the children at the playground were boys in the end? Express your answer as a mixed number.
Level 3
The usual price of a notebook sold at Shop A and B is $20. During a sale, a discount of 20% is given to every notebook sold at Shop A. At Shop B, a discount of 50% is given to the 3rd notebook for every 3 notebooks sold. How much cheaper would it be if Lily buys 8 notebooks from Shop A instead of Shop B?
