In the school hall, chairs were arranged in rows of 15. During a function, 30 chairs were added to accommodate the number of people. The chairs were rearranged to form rows of 12. As a result, there were 6 more rows.
- How many chairs were there in the extra 6 rows?
- How many chairs were there in the school hall in the end?
|
First arrangement |
Second arrangement |
Number |
1 u |
1 u + 6 |
Value |
15 |
12 |
Total value |
15 u |
12 u + 72 |
(a)
Number of chairs in the extra 6 rows
= 6 x 12
= 72
(b)
Total number of chairs in the first arrangement
= 1 u x 15
= 15 u
Total number of chairs in the second arrangement
= 12(1 u + 6)
= 12 u + 72
If 30 chairs were included in the first arrangement, the total number of chairs in the first arrangement and the second arrangement will be the same.
15 u + 30 = 12 u + 72
15 u - 12 u = 72 - 30
3 u = 42
1 u = 42 ÷ 3 = 14
Number of chairs in the school hall in the end
= 14 x 15 + 30
= 210 + 30
= 240
Answer(s): (a) 72; (b) 240