PSLEIn a school hall, chairs were arranged in rows such that there were exactly 15 chairs in each row. For a concert, Liam brought 9 more chairs into the school hall and rearranged all the chairs. There are now exactly 9 chairs in each row and 11 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 + 11 |
Value |
15 |
9 |
Total value |
15 u + 9 |
9 u + 99 |
Number of rows at first = 1 u
Number of rows in the end = 1 u + 11
Number of chairs at first after the 9 chairs were brought in
= 15 x 1 u + 9
= 15 u + 9
Number of chairs in the end
= 9 x (1 u + 11)
= 9 u + 99
The total number of chairs is equal.
15 u + 9 = 9 u + 99
15 u - 9 u = 99 - 9
6 u = 90
1 u = 90 ÷ 6 = 15
Number of chairs in the end
= 9 u + 99
= 9 x 15 + 99
= 234
Answer(s): 234