PSLEThere were a total of 129 tables and chairs in a hall. There were 2 times as many chairs as tables. After 21 chairs and some tables were thrown away, there were 5 times as many chairs as tables left. How many tables were thrown away from the hall?
|
Tables |
Chairs |
Total |
Before |
1 u |
2 u |
129 |
Change |
- ? |
- 21 |
|
After |
1 p |
5 p |
|
Number of tables and chairs at first
= 2 u + 1 u
= 129
3 u = 129
1 u = 129 ÷ 3 = 43
Number of chairs at first
= 2 u
= 2 x 43
= 86
Number of chairs left
= 86 - 21
= 65
5 p = 65
1 p = 65 ÷ 5 = 13
Number of tables thrown away from the hall
= 43 - 13
= 30
Answer(s): 30