Two minutes ago, 60% of the children in a parade square were boys. 28 children left the parade square. As a result, the number of boys decreased by 20% and the number of girls decreased by 90%. How many children are in the parade square at first?
| |
Boys |
Girls |
Total |
| Before |
5 u |
2 u |
7 u |
| Change |
- 1 u |
- 1.8 u |
- 2.8 u |
| After |
4 u |
0.2 u |
4.2 u |
60% =
60100 =
35Number of boys who left the parade square
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of girls who left the parade square
= 90% x 2 u
=
90100 x 2 u
= 1.8 u
Total number of children who left the parade square
= 1 u + 1.8 u
= 2.8 u
2.8 u = 28
1 u = 28 ÷ 2.8 = 10
Number of children in the parade square at first
= 5 u + 2 u
= 7 u
= 7 x 10
= 70
Answer(s): 70
