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.
