In the school hall, chairs were arranged in rows of 10. During a function, 30 chairs were added to accommodate the number of people. The chairs were rearranged to form rows of 8. As a result, there were 9 more rows.
- How many chairs were there in the extra 9 rows?
- How many chairs were there in the school hall in the end?
|
First arrangement |
Second arrangement |
Number |
1 u |
1 u + 9 |
Value |
10 |
8 |
Total value |
10 u |
8 u + 72 |
(a)
Number of chairs in the extra 9 rows
= 9 x 8
= 72
(b)
Total number of chairs in the first arrangement
= 1 u x 10
= 10 u
Total number of chairs in the second arrangement
= 8(1 u + 9)
= 8 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.
10 u + 30 = 8 u + 72
10 u - 8 u = 72 - 30
2 u = 42
1 u = 42 ÷ 2 = 21
Number of chairs in the school hall in the end
= 21 x 10 + 30
= 210 + 30
= 240
Answer(s): (a) 72; (b) 240