PSLEThere were a total of 136 tables and chairs in a hall. There were 3 times as many chairs as tables. After 18 chairs and some tables were thrown away, there were 4 times as many chairs as tables left. How many tables were thrown away from the hall?
|
Tables |
Chairs |
Total |
Before |
1 u |
3 u |
136 |
Change |
- ? |
- 18 |
|
After |
1 p |
4 p |
|
Number of tables and chairs at first
= 3 u + 1 u
= 136
4 u = 136
1 u = 136 ÷ 4 = 34
Number of chairs at first
= 3 u
= 3 x 34
= 102
Number of chairs left
= 102 - 18
= 84
4 p = 84
1 p = 84 ÷ 4 = 21
Number of tables thrown away from the hall
= 34 - 21
= 13
Answer(s): 13