Fifteen minutes ago, 70% of the children in a basketball court were girls. 57 children left the basketball court. As a result, the number of girls decreased by 20% and the number of boys decreased by 60%. How many children are in the basketball court at first?
| |
Girls |
Boys |
Total |
| Before |
10 u |
3 u |
13 u |
| Change |
- 2 u |
- 1.8 u |
- 3.8 u |
| After |
8 u |
1.2 u |
9.2 u |
70% =
70100 =
710Number of girls who left the basketball court
= 20% x 10 u
=
20100 x 10 u
= 2 u
Number of boys who left the basketball court
= 60% x 3 u
=
60100 x 3 u
= 1.8 u
Total number of children who left the basketball court
= 2 u + 1.8 u
= 3.8 u
3.8 u = 57
1 u = 57 ÷ 3.8 = 15
Number of children in the basketball court at first
= 10 u + 3 u
= 13 u
= 13 x 15
= 195
Answer(s): 195
