PSLEIn a school hall, chairs were arranged in rows such that there were exactly 25 chairs in each row. For a concert, Henry removed 4 chairs from the school hall and rearranged all the chairs. There are now exactly 9 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 |
25 |
9 |
Total value |
25 u - 4 |
9 u + 108 |
Number of rows at first = 1 u
Number of rows in the end = 1 u + 12
Number of chairs at first after the 4 chairs were removed
= 25 x 1 u - 4
= 25 u - 4
Number of chairs in the end
= 9 x (1 u + 12)
= 9 u + 108
The total number of chairs is equal.
25 u - 4 = 9 u + 108
25 u - 9 u = 108 + 4
16 u = 112
1 u = 112 ÷ 16 = 7
Number of chairs in the end
= 9 u + 108
= 9 x 7 + 108
= 171
Answer(s): 171