On Wednesday, there were 10 more children than adults at the bowling alley. On Thursday, the number of children decreased by 90% and the number of adults decreased by 70%. There were 21 people on Thursday. How many children were there on Thursday?
| |
Children |
Adults |
Total |
Comparing children
and adults at first |
10 more |
|
|
| Before |
10 u |
+ 10 |
10 u |
|
| Change |
- 9 u |
- 9 |
- 7 u |
|
| After |
1 u |
+ 1 |
3 u |
21 |
90% =
90100 =
910 90% x 10 =
910 x 10 = 9
10 - 9 = 1
70% =
70100 =
710 Total number of people on Thursday
= 1 u + 1 + 3 u
= 4 u + 1
4 u + 1 = 21
4 u = 21 - 1
4 u = 20
1 u = 20 ÷ 4 = 5
Number of children on Thursday
= 1 u + 1
= 1 x 5 + 1
= 5 + 1
= 6
Answer(s): 6
