PSLEIn a school hall, chairs were arranged in rows such that there were exactly 30 chairs in each row. For a concert, Ben removed 8 chairs from the school hall and rearranged all the chairs. There are now exactly 7 chairs in each row and 12 more rows than before. How many chairs are there in the school hall for the concert in the end?
|
Before |
After |
Number |
1 u |
1 u + 12 |
Value |
30 |
7 |
Total value |
30 u - 8 |
7 u + 84 |
Number of rows at first = 1 u
Number of rows in the end = 1 u + 12
Number of chairs at first after the 8 chairs were removed
= 30 x 1 u - 8
= 30 u - 8
Number of chairs in the end
= 7 x (1 u + 12)
= 7 u + 84
The total number of chairs is equal.
30 u - 8 = 7 u + 84
30 u - 7 u = 84 + 8
23 u = 92
1 u = 92 ÷ 23 = 4
Number of chairs in the end
= 7 u + 84
= 7 x 4 + 84
= 112
Answer(s): 112