PSLEThere were a total of 138 tables and chairs in a hall. There were 2 times as many chairs as tables. After 12 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 |
138 |
Change |
- ? |
- 12 |
|
After |
1 p |
5 p |
|
Number of tables and chairs at first
= 2 u + 1 u
= 138
3 u = 138
1 u = 138 ÷ 3 = 46
Number of chairs at first
= 2 u
= 2 x 46
= 92
Number of chairs left
= 92 - 12
= 80
5 p = 80
1 p = 80 ÷ 5 = 16
Number of tables thrown away from the hall
= 46 - 16
= 30
Answer(s): 30