PSLEIn a school hall, chairs were arranged in rows such that there were exactly 19 chairs in each row. For a concert, Ivan removed 4 chairs from the school hall and rearranged all the chairs. There are now exactly 15 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 |
19 |
15 |
Total value |
19 u - 4 |
15 u + 180 |
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
= 19 x 1 u - 4
= 19 u - 4
Number of chairs in the end
= 15 x (1 u + 12)
= 15 u + 180
The total number of chairs is equal.
19 u - 4 = 15 u + 180
19 u - 15 u = 180 + 4
4 u = 184
1 u = 184 ÷ 4 = 46
Number of chairs in the end
= 15 u + 180
= 15 x 46 + 180
= 870
Answer(s): 870